Gearbox oils are a separate group of oils. The oil for automatic transmission has a higher viscosity, it uses completely different additive packages than in engine oil. This oil is subject to higher requirements for its antiwear, antifriction and antioxidant properties, since the oil service life in automatic transmissions ranges from 30-40,000 km to the entire life of the car. The diverse tasks performed by oil in automatic transmissions impose very high requirements and restrictions on its properties. The oil cools, lubricates, provides frictional clutch and transmits torque. The operating temperature range of oil in automatic transmission is from 90 ° C to 150 ° C. Completely different materials used in automatic transmission friction pairs (steel - bronze, steel-cermet, steel - steel, steel - composite materials) cause the use of different packages of antifriction additives in the oil, which are not always compatible with each other. In this case, it is necessary to prevent aeration, and as a result, foaming of the oil in the automatic transmission, which occurs when the flow of hot oil swirls under pressure. The result of aeration and foaming of the oil is oil oxidation and corrosion of the materials from which the automatic transmission is made. The automatic transmission is a highly loaded unit, during the operation of which part of the energy converted into translational motion is spent on internal friction of the oil, which leads to its significant heating. As a result, the requirements for the oil viscosity in automatic transmissions are opposite: to reduce the internal friction of the oil during the operation of the torque converter, the oil must have a low relative viscosity, and to ensure lubrication of the gears, on the contrary, the oil must have a sufficiently high viscosity.
Types of oil for automatic transmission.
There are three main types of oils used in automatic transmissions: Dexron, Mercon and MB. This is due to the historical specification for automatic transmission oil. The first oil specification was formulated in 1949 by GM. At the turn of 1990. the requirements of different specifications have become almost the same so much that all gearbox oils have become interchangeable. Dexron IV oils are designed for use in automatic transmissions with an electronically controlled torque converter clutch.
Oil specifications, automatic transmission GM (GENERAL MOTORS)
GM first faced the need to develop and formulate separate specifications for the classification of fluids for automatic transmissions (Automatic Transmission Fluids - ATF, another name for automatic transmission fluid).
ATF type A denotes a type of transmission oil that is suitable for automatic transmissions in passenger cars. Oils that have passed the tests have received AQ qualification numbers. AQ qualification numbers were assigned by agreement with GM by Amour Research in the "Amour Qualification N" format. The specifications have lost their relevance.
DEXRON (B) - current and current specifications for GM automatic transmission fluids (oils for automatic transmissions). Many manufacturers or buyers of such automatic transmissions also use these specifications. The admission is made under the so-called type "B".
DEXRON II, III, IV are the latest GM oil (automatic transmission fluids) specifications. They tighten the requirements for fluids for automatic transmissions. They include and exceed all previous specifications, meet increased requirements for environmental safety. Allison Fluids: "Type C1" and "Type C2" specifications are replaced by DEXRON II specifications; "Type SZ" - MIL-L-2104D.
FORD specifications
Fluids for automatic transmission "type F", according to the latest specifications Ford M2C33F and M2C33G, in some parameters (for example, in terms of the coefficient of friction) differ significantly from DEXRON oils. The main difference is the coefficient of friction, which in the case of Ford increases with decreasing sliding speed, while General Motors, on the contrary, requires a decrease in the coefficient of friction in the same case.
According to the Ford M2C138-CJ and M2C166H specifications, fluids for automatic transmissions of ATF type can be partially replaced with DEXRON II fluids, however, a complete oil change in the automatic transmission is most preferable.
ATF Dexron II, Plus Dexron III and ATF-A series automatic transmission fluids are designed for transmissions operating under high mechanical and thermal loads; they can be used in transmissions of passenger cars of any automaker, hydraulic power steering and clutch units. ATF group automatic transmission fluids are produced under two brands: ATF II D Plus and Dexron III. ATF II D Plus is designed for use in heavily loaded transmissions and belongs to the Extrimal Pressure category. A balanced high-tech additive package provides high anti-corrosion properties. In terms of its parameters, this automatic transmission oil meets the requirements of most of the world's leading automakers. Dexron III is used in automatic transmissions of passenger cars, light commercial vehicles and minivans.
Other specifications.
In addition to the General Motors and Ford specifications for automatic transmissions, the factory specifications of Chrysler, MAN, Toyota, Allison, Renk, Voith, ZF are used. For cars sold in Europe and with automatic transmissions made by ZF, automatic transmission oils are selected according to GM specifications. In the automatic transmissions of Audi, BMW and Mercedes of the last years of production, only synthetic oil for automatic transmissions is poured!
Oil change in automatic transmission.
Changing the oil in the automatic transmission must be carried out in strict accordance with the operating instructions for your car! Violation of oil change intervals, as a rule, leads to a sharp deterioration in the functionality of the automatic transmission and a reduction in its service life. Under severe operating conditions of the car (driving with a full load, driving with a trailer, frequent engine braking, using cars on roads with unpaved, sandy and snow surfaces, high or low ambient temperatures, wheel slip, using the car in start-stop mode (city traffic jams) ), sharp acceleration from standstill - all automakers recommend reducing the oil change intervals in the gearbox by half. In practice, this leads to a reduction in the service interval for automatic transmission oil in Moscow to 30, maximum 40,000 km! Change the oil more often - your automatic transmission will last longer!
Mixing automatic transmission oils of different types when changing them.
Mixing is possible, well, better to avoid it. For quick identification of the oil poured into the automatic transmission, a dye is added to the oil, the addition of which does not change the properties of the oil. However, in conditions where you cannot clearly identify the previously filled oil, it is strongly recommended to carry out a complete change of the automatic transmission oil. The cost of even the smallest automatic transmission repair is ten times higher than the cost of a complete oil change in an automatic transmission.
Non-original automatic transmission oil for your car.
When changing the oil in automatic transmissions, some automakers, for example Honda and Mitsubishi, require the use of specialized oils under their brands. It is necessary to understand that neither Honda nor Mitsubishi produce oil on their own, but order its production from leading petrochemical corporations (ExxonMobil, BP, Chevron, PetroCanada, and so on). In addition, information has recently appeared in the press that automakers have begun to place orders for motor and transmission oils, poured into engine units on a conveyor, at private factories in Europe (Ravenol, Addinol, etc.) according to their specifications. At the same time, gear and engine oils produced by Ravenol under its own brand for use in cars, for example, Hundai and KIA, for the most part of their performance are superior to oils produced by the same Ravenol, but distributed in packaging and under the Hundai brand - the automaker saves money and is not interested ensuring that the car works without breakdowns and after the expiration of the warranty period. Therefore, according to experts, the use of oils produced by private European factories directly for use in automatic transmissions of cars of one or another car manufacturer is the best option for those car owners whose car warranty period has already expired.
"Transmission oil in an automatic transmission is usually changed every 60,000 km." (From the "Repair and Maintenance Manual"). The masters of the firm tell about why, why, what and how.
Technicians are serious people, like the goddess Technics, whom they worship. Technique does not tolerate inaccuracies, or, God forbid, any jokes. She is extremely accurate in everything, including language, that is, terminology. It is said "valve to scrape", which means it is "valve" and it is "to scrape". And if, on the contrary, it is written: "to breed a Swede", then there is nowhere to go - it is necessary to breed ...
About terminology
The conversation about her did not come by accident. From the point of view of terminology, the phrase "Guidelines" given by us does not "hold out" a little. Smells, sorry, technical "fenny".
And the point is as follows. It is not oil that is poured into automatic transmissions, but an automatic transmission fluid specially developed for these purposes, which is confirmed by the English abbreviation ATF (automatic transmission fluid), which is always present on the packaging of this product.
It would seem, what's the difference - oil or liquid? But no. There is a difference, and a significant one. In technology, it is customary to call oil a substance used primarily for lubricating the rubbing surfaces of parts and mechanisms. In contrast, the fluid used in automatic transmission performs many other functions that are completely unusual for oil. And it works in conditions that are beyond the limit for engine and transmission oils. Let's talk about this.
The fundamental difference between automatic transmissions and mechanical transmissions is that there is no rigid connection between the engine crankshaft and the automatic transmission input shaft when the car is moving. The role of the well-known clutch is assigned to the hydrodynamic transformer (GDT). It is he who transfers torque from the engine to the box. The main character, i.e. the working fluid is ATF.
In addition, ATF is used to transmit the control pressure to the clutches of the multi-plate clutches, causing the inclusion of a particular gear.
In the process of operation, the units and mechanisms of the automatic transmission experience serious thermal loads. The temperature on the surface of the clutches at the time of gear shifting reaches 300-400 o С. There is an intensive heating of the torque converter. When driven at full power, its temperature can reach 150 o C.
Providing heat removal from the automatic transmission and dumping heat into the atmosphere also occurs with the help of transmission fluid.
Moreover, ATF must still, without oxidizing at high temperatures and without foaming, provide lubrication of gear mechanisms, bearings and other parts subject to abrasion and scoring. For this, a whole complex of additives is added to the liquid. Moreover, it should fully manifest its properties in the entire range of permissible operating temperatures: from -40 o to +150 o C.
One cooks food, one washes, one brings up children ... It's hard!
And you say: butter ...
Why?
Chemists-technologists have tried their best to create a "tricky" fluid, but still have not been able to provide such a resource of its work, so that when operating a car, one could forget about the very existence of ATF. There are several reasons for this.
Firstly, even if the automatic transmission is sealed and has no leaks, during operation the amount of fluid decreases due to the removal of its vapors through the automatic transmission cavity ventilation system, equipped with a valve - "breather". Therefore, during maintenance, it is necessary to top up the transmission fluid to the operating level.
This procedure is easy to perform if the automatic transmission has a tube for monitoring the fluid level with a dipstick. Many modern boxes are not equipped with a probe. This is especially true for European manufacturers who are persistently trying to remove the inept car owner (and they probably have the majority) from servicing personal equipment.
Secondly, during long-term operation, the transmission fluid sooner or later loses the physicochemical properties that are so necessary for it to perform numerous useful functions. Due to the evaporation of light fractions, its viscosity increases above the permissible level. Miraculous additives develop their resource.
The transmission fluid must remain clean in a normally operating box throughout its entire service life. Only a slight change in its color is allowed - it darkens.
A dirty black liquid with a specific burning smell is an indicator that the box does not need a fluid replacement, but a serious repair.
Experts recommend changing the oil after a car has driven 50-70 thousand km, if the car is used normally, and after 30-40 thousand km - with very intensive ("police") driving. Note again that the indication for replacing the fluid is not its color, but only the mileage of the machine. If, of course, the automatic transmission is working properly.
What?
The recommended brand of transmission fluid is usually indicated in the Repair and Maintenance Manual of the vehicle. If this information is not available, it is useful to know the following. Despite the variety of brands, what you need is always labeled "ATF" on the packaging. The most common ATF brand is Dexron (usually with Roman numerals I, II or III). The higher the number, the higher the quality of the fluid and the more modern the automatic transmission in which it is used. For Ford vehicles it is recommended to use Dexron-Megsop fluid. These fluids, like the vast majority of those currently on the market, are mineral based and red in color. All of them are usually compatible with each other.
As usual, French manufacturers are original, developing yellow and green ATFs for some of their cars. It is strongly discouraged to mix them with liquids of our native red color, otherwise, no matter what happens ...
Synthetic ATF has recently appeared on the market. The accompanying technical documentation states that "synthetics" provides good fluidity at temperatures down to -48 o С, better stability at high temperatures and increased service life. At the same time, synthetic transmission fluid is fully compatible with mineral ATFs (again, unlike synthetic engine oil).
The cost of one liter of "synthetics" is about 10 US dollars, while a liter of mineral ATF costs 3-4 dollars.
We will not dare to recommend it for use "anywhere". This is the case, as they say, of the head and the wallet. If the use of synthetics is specifically stipulated by the "Guide ..." (for example, for an automatic transmission of the 5NRZO type, with which some brands of BMW cars are equipped), then this is a sacred thing - you will have to go at great expense.
In total, automatic transmissions of various types can fill from 7 to 15 liters. transmission fluid. However, this does not mean at all that you need to purchase such an insane amount of ATF for replacement. This is where the fundamental difference between the process of changing the fluid and changing the engine oil in the engine is manifested.
The fact is that when replacing ATF, you will be able to drain no more than 50% of the total volume. Your dexterity and skill have nothing to do with it - these are the design features of the automatic transmission. You can completely change the transmission fluid only when the box is completely disassembled. Before going to the store, carefully study the technical documentation. Sometimes it indicates the full volume of ATF, sometimes the volume to be replaced. Don't forget to get a new filter element as well.
How?
You need to drain the transmission fluid from a heated automatic transmission, for which, before draining, you need to drive a car a dozen or more kilometers.
Take care of precautions: the temperature of the liquid can be very high. As a rule, a drain plug is provided for draining, but ... today, apparently, is not our day. We're out of luck. Or rather, the master Mikhail Gulut-kin, who busily sat down on a chair under the car, was unlucky: the A4LD box, which the Ford Scorpio is equipped with, does not have a drain plug. Have you forgotten? It was reasonably suggested that this is not forgetfulness, but protection from the fool: if you want to drain, unscrew the pallet. Unscrew it - you will see the filter.
In some automatic transmission designs, for example, on Mercedes cars, it is possible to drain the transmission fluid not only from the sump, but also from the torque converter through a threaded plug.
After removing the pallet, do not rush to rinse it. First, look if there are any foreign deposits on its inner surface, indicating mechanical wear of the automatic transmission parts. Only a small amount of metal dust is allowed on the trapping magnet located in the corner of the pan.
When servicing certain types of automatic transmissions, opening the pallet, you will not find the filter element. Don't worry - it also happens. For example, in a box of the AW50-40 LE brand installed on an Opel Vectra, the filter is located so that it can be replaced only during a major overhaul of the box.
When installing a new filter element, be sure to install all of the gaskets and O-rings included in the filter kit.
After filling the required amount of ATF, set the automatic transmission mode selector to the position required to check the fluid level and check it with the engine running.
After making a short trip, repeat the measurement and bring the level to normal. Inspect the pallet for leaks.
Other details of the oil change procedure can be clarified by studying the photographic materials. Just business. As one of our acquaintances says, "Drive and don't be sad!"
The gears do not run on traditional gear oils. They are filled with special ATF oil. This liquid is a high-index formulation on a mineral or synthetic base. These automatic transmission fluids allow for the operation of the systems that monitor and control gear changes. Also, through this fluid, torque is transmitted from the engine to the automatic transmission. Additionally, ATF oil lubricates the friction parts and cools them.
How ATFs were created
For the first time an automatic transmission was created in 1938. This design was named Hydramatic. It featured a vacuum gear shift system. This unit was created by Pontiac engineers. Even then, the company was part of the General Motors auto concern.
Since before the launch of any innovative development, they preferred to check it and test it in every possible way, the new automatic transmission was installed on Oldsmobile. The tests went well. And now, in the 39th year, "Hydromatic" was installed as an option on the Oldsmobile Custom 8 Cruiser. This option cost $ 57.
General Motors' role in creating the first ATF
By the end of the 40s, automatic transmission had become a familiar part of cars. And it is not surprising that the first ATF oil for automatic transmissions was created by General Motors specialists. This was the world's first specification for a transmission fluid. It was called Type A. The liquid was created in 1949. Then, GM began to develop transmission oils, and later to classify, put forward the most stringent requirements for them. The products that were created in the laboratories of General Motots, due to the lack of competition, have become the international standard for working fluids for any type of automatic transmission.
From to new technologies
In 1957, the already successfully existing specification was revised and it was decided to add one small new application - Type A Suffix A transmission fluid (abbreviated name ATF-TASA). After 10 years, we created specification B (this is ATF Dexron-B).
Blubber was used as the main ingredient that made the liquid lubricating, a fat obtained from whales. But then the development of technologies in the production of automatic boxes forced the concern to introduce something new. So, in 1973, a new specification, Dexron 2C, was developed. In 1981 it will be replaced by Dexron-2D. After a flurry of negativity from animal advocates fell upon the corporation, as well as after the ban on catching whales, the company in 1991 creates the innovative Dexron-2E formula. The difference between this product is that it is created on a synthetic basis. Previously, the lubricant was produced on a mineral basis.
Birth of Dexron-4
In 1994, the entire world community learned about the new specifications, which laid out new requirements for viscosity properties and temperature characteristics. Also, the specification implied more improved frictional properties. These are Dextron-3F and Dextron-3G. Dextron-3H comes out 8 years later. But the most modern and most rigid is ATF Dexron-4. Of course, there are other specifications from other car manufacturers today as well. These are such giants as Ford, Toyota, Huinday and others.
How is ATF different from other gear oils?
To understand the difference, you need to approach the issue from afar. Cars use oils for the engine, gearboxes, hydraulic boosters and ATF oil. What are the similarities between all these fluids? These oils are based on hydrocarbons, which are obtained through the processing of fossil fuels. This gives some similarities in performance. All of these products have lubricating properties, increase sliding between rubbing surfaces.
Also, all these fluids have good heat dissipation characteristics. They are similar in consistency. This is where all the similarities end. This is sometimes the reason for gross errors when a novice motorist pours oil for "mechanics" into the automatic transmission, and brake fluid in the power steering.
Basic properties of ATF
ATF oil is one of the most complex fluids in its composition among all lubricating mixtures used in a modern car. This grease has high requirements and standards. The oil should have a lubricating effect - due to this, friction is reduced, and at the same time, wear in the gearbox elements decreases. In this case, the forces of friction in the friction groups should increase. This will reduce slippage and other knots.
Also one of the important properties is heat dissipation. The oil has high thermal conductivity and fluidity characteristics. In this case, the liquid should not foam during operation. An important point is stability, namely the absence of oxidative processes when heated to high temperatures at the time of contact with oxygen. Additionally, the oil must have anti-corrosion properties. This is necessary in order to prevent the formation of corrosion on the internal components of the mechanism. Automatic transmission fluid must be hydrophobic (this is the ability to push moisture out of the surface). In this case, it is necessary that the fluid retains its flow characteristics and hydraulic characteristics. ATF grease has stable characteristics and a high compression ratio over the widest possible temperature range. Another point is a decrease in penetration through automatic transmission and the presence of a dye.
Typical characteristics for automatic transmission lubricants
Consider several ATF specifications, characteristics and numbers. For the Dexron-2 specification, the kinematic viscosity is 37.7 at 40 ° C. At 100 degrees, the same parameter will be 8.1. For Dexron-3, the kinematic viscosity is not standardized at all, as well as for other specifications.
The Brooksfield ATF viscosity for Dexron-2 at 20 degrees should be 2000 mPa, at 30 - 6000 mPa, at 40 - 50 000 mPa. The same parameter for Dexron-3 will be 10, if the pressure is 1500 MPa. Flash point - not lower than 190 degrees for Dexron-2. For Dexron-3 - this parameter is 179 degrees, but not higher than 185.
Compatibility of ATF oils
Any oil (no matter whether it is mineral or synthetic) can be mixed without any consequences. Naturally, more modern fluids have improved characteristics and properties. If a modern liquid is added to an ordinary one, this will improve the properties of the filled oil. The older the specification, the lower the performance it will have. Also, the shelf life of ATF oil is an order of magnitude lower. Experts recommend changing this fluid every 70 thousand kilometers. It should be noted that many modern manufacturers do not regulate the replacement period for this fluid. It is cast for the entire service life. But when a car cares for 200 thousand kilometers on one oil, this is not very good. The fact is that the fluid in the automatic transmission is working. It is she who transmits the torque from the engine to the wheels. This oil is constantly active, even when the vehicle is at neutral speed. Over time, it collects waste products.
This is metal shavings that clog the filter and sensors. As a result, the box ceases to function normally. Now to the question of compatibility. No brand will ever fully disclose all information regarding the composition and properties of the liquid produced. Often, manufacturers are limited to marketing information and advertising that compels them to buy only a specific product. But often this information is not substantiated. For transmissions with rigid engagement of torque converter locks, it is recommended to use fluids with constant frictional characteristics.
For automatic transmissions with GTP blocking, products with variable properties should be filled. And finally, regardless of the automatic transmission model, all parts, bearings, gears and other elements are made from the same materials. This means that the various types of ATF do not particularly differ from each other.
On the features of application and compatibility
If the oil in the box is changed entirely, then it is best to purchase a more expensive product. In this case, it is necessary to take into account constant or variable friction characteristics. If your budget is tight, then even a multi-purpose ATF will do. Its use will not affect the quality of the box. If the liquid is topped up, then experts recommend using products with a class higher or at least not lower than the filled one. But if its resource has reached 70 thousand kilometers, a complete replacement is required. Additional flushing is desirable. This operation requires an additional 20 liters of oil. It is not cheap, but judging by the reviews, this operation perfectly flushes the chips. And its presence, as you know, complicates the operation of an automatic transmission.
So, we found out what ATF oil for automatic transmissions is.
To fully understand this issue, you need to go from afar. Let's consider what oils are generally used in cars, how they are fundamentally different. Without going into details, these are engine oils, transmission (gear) oils, hydraulic booster oils, ATP and brake fluid. The similarity of all the listed oils, firstly, is that they are based on hydrocarbons obtained by processing fossil hydrocarbon raw materials, which, accordingly, gives some similarity in properties. All of them have a lubricating, increasing sliding between rubbing surfaces and a hydrophobic (downward-repelling) effect, as well as the ability to remove heat. Slightly similar in appearance: oily to the touch with similar in the first approximation, this is where the similarity in properties ends.
This sometimes gives rise to irreparable errors, when, for example, engine oil is poured into the automatic transmission, and brake fluid is poured into the hydraulic booster. Naturally, these actions are immediately followed by a breakdown of the unit. So what is it that globally differs ATF (Automatic Transmission Fluid - fluid for automatic transmissions) from all other substances poured into car devices.
ATF properties
The fact is that ATF is the most complex liquid in a car in terms of composition, from which a number of properties are required, sometimes contradicting each other.
- Lubricating effect: reduced friction and wear in bearings, bushings, gears, pistons, solenoid valves.
- Increase (modification) of friction forces in frictional groups: reduction of slippage (shift) between the clutches of the clutch packs, brake bands, torque converter lockup.
- Heat removal: quick heat removal from the friction zone due to thermal conductivity and fluidity.
- Foam suppression: no foaming in areas of contact with air.
- Stability: no oxidation when heated to a high temperature and in contact with atmospheric oxygen for the longest possible period.
- Anti-corrosion: prevents the formation of corrosion on the internal parts of the automatic transmission.
- Hydrophobicity: the ability to push moisture out of the serviced surfaces.
- Fluidity and hydraulic properties: the ability to maintain stable fluidity and hydraulic properties (compression ratio) in a wide temperature range from -50 C to +200 C.
So what should you fill in the automatic transmission and how to add ATF, if the required ATF brand is not at hand or it is generally not known what is filled in the automatic transmission?
To simplify the answer, let's first make a few statements.
- Any type of ATF - mineral water, semi-synthetics or pure synthetics are mixed with each other without any negative consequences. More modern ATFs have better performance and properties.
- The addition of a more modern type of ATF to a less modern type improves its properties.
- The less modern ATF, the worse its properties and therefore it must be changed more often, but even the most dense ATF of the DEXTRON II type will operate the most modern automatic transmission of the ZF6HPZ6 type without any problems. Tested in practice!
- No manufacturer discloses full information about the composition and properties of the ATF they produce, limiting themselves to general advertising recommendations. The exception is special highly modified oils, into which their manufacturers do not know what they have mixed and promise a fantastic effect. Such liquids, if there is a desire to use them, it is better to fill in with nothing, since the effect is unpredictable.
- Manufacturers' instructions on the use of ATF in their products are largely dictated by the goal of increasing profits and are not always technically justified.
- It is advisable (but not necessary) to use ATF with constant frictional properties for automatic transmissions with rigid inclusions of torque converter blocking, and ATF with variable functional properties for automatic transmissions with main engine blocking having a controlled slip mode, the rest is not important.
- All glands, gears, bearings, clutches, seals, etc. in automatic transmissions they consist of materials of the same properties regardless of the automatic transmission manufacturer, the nuances are not very significant, which means that different ATFs cannot have fundamentally different properties.
Summarizing all of the above, we draw the following conclusion: if you refuel or change ATF in an automatic transmission entirely, it is advisable to use a more modern and apparently more expensive ATF, considering only its frictional properties (variable or constant) for your automatic transmission. If the budget is limited, then you can fill in any ATF that is suitable for the price - this will not noticeably affect the operation of the automatic transmission, but the ATF will have to be changed more often. Manufacturers' recommendations can be ignored altogether. When pouring ATF into an existing fluid, if the same grade is not available, it is necessary to use a fluid with a class not lower than the main one, i.e. DEXTRON III c. DEXTRON II can be topped up, but on the contrary it is undesirable, because if the ATF properties are reduced in the initial automatic transmission, it may start to work worse, but if you don’t know at all what is flooded and are afraid to harm, add the most expensive modern ATF type DIV-DVI, again in according to the frictional properties.
ATF Roster
Due to the need to obtain such a large number of multidirectional properties, the ATF composition is extremely complex and is not disclosed in detail by Manufacturers. In open information, there are only general data on the chemical and molecular composition of the main additives, it is these additives (additives) that ultimately form the set of properties that ATF should have, detailed formulas of substances and their interactions are classified.
The chemical composition of ATF consists of two main parts - a base base and an additive package. The base stock is the direct carrier fluid that makes up the bulk. According to its type, the base is divided into three main groups: mineral, semi-synthetic and synthetic. A mixture of a mineral and synthetic base is also used, which is sold as synthetic. Mineral bases include paraffinic (paraffinics) and naphthenic oils, their group in the XHVIYAPI ATIEL classification systems (the tehnical association of the european lubricans american petrolen Institute). Semi-synthetic or conditionally synthetic are hydrated (hidroisomerised) mineral base oils that are considered improved, but relative to the first group, their classification is VHVI, one of the Yubase brand names. But the truly synthetic base group is the polyalphaolefin HVHVI (PAD) oils. The technology for their production is extremely complex and expensive at the moment, and in most cases the commercially available synthetic ATFs consist partially of a synthetic base with the addition of a mineral or conditionally synthetic main component, which you will never be notified of on the package.
Additives GATF
The second part of the ATF chemical composition is the additive package. Their chemical composition is also classified by manufacturers, and there is publicly available information on the total chemical composition and percentage of ions of various substances: phosphorus - P +, zinc - Zn +, boron - Bo, barium - Ba, sulfur - S, Nitrogen, Magnesium, and etc.
In fact, these ions are part of polyesters, which create additional chemical compounds in the mixture, enhancing certain properties of the additives.
That is why we are always talking about a package of additives with certain characteristics.
Let us consider the ionic composition of the additive package of the most common ATFs of the DEXTRON III / MERCON standard. The total amount of additives in DIII in relation to the base oil is 17%, of which in the composition of ionizers:
- Phosphorus - 0.3% AW in 2-ethyl-hexyl-phosphoric acid, improves antiwear properties in ZDDP additive.
- Zinc - 0.23% in ZDDP zinc-diethyl-dithiophosphate - antioxidant properties, antiwear.
- Nitrogen - 0.9% AW additive (Anti-Wear)
- Boron - 0.16% AW additive, enhances detergent properties by enhancing ZDDP.
- Calcium - 0.05%, in the composition of calcium phenates - a detergent effect, plus a dispersant in the base additive TBN, anti-corrosion effect.
- Magnesium - 0.05% detergent properties in the base additive, acidity reduction, anti-corrosion effect.
- Sulfur - 0.55% AW additive, plus friction modifiers (FM), antiwear properties in EP.
- Barium - various%, partic late control.
- Siloxane - 0.005% active foam suppressor.
The ions listed below are part of additives with complex formulas, the details of which are classified, some of their names and general chemical formula:
- ZDP - zinc phosphate, anti-corrosion effect
- ZDDP - - dithio-phosphate, antioxidant, anti-corrosive.
- TCP - Tricresyl Phosphate, Increased Heat Resistance.
- HP - chlorinated paraffin wax, high temperature resistance.
- MOG - glycerin monoplast
- Stearic acid
- PTFE - Teflon (almost never used in ATF)
- SO - sulfated EP (Extrime Pressure additive) stabilizes the properties at overpressure.
- ZCO - zinc carooxylate, corrosion inhibitor.
- NA is a group of alkylated benzenes.
- POE - ethers.
- TMP - lineoleic esterolinols
- MODTP
In total, about a hundred of such additives have been developed, and one additive package can include up to 20 complex substances, which, when combined, give a cross-over effect that creates the specified characteristics of ATF.
History of ATF creation
Experiments to create automatic transmissions began en masse in the 20s of the 20th century, but at that time no one seriously thought about changing the properties of hydraulic fluids used in them. The first big breakthrough came in 1949, when General Motors introduced the world's first mass-produced ATF, which received the Type A index. It was based on petroleum mineral oil, and sperm whale sperm oil was used as the only additive. Sperm fat was secreted from the unfortunate animal by a special gland and accumulated in two bags located in the hollows between the bones in the upper part of the skull. These bags served the whale as resonators for the ultrasonic signals it emitted. After killing and cutting the whale, the sperm fat was frozen from the contents of the sperm sacs and was hydrated, resulting in a substance called Cetin, the chemical formula of which is С15Н31СООС16Н33, which was used as the main component of the first ATF.
The quality of ATF Type A turned out to be so high that the mixture practically did not require any modifications, based on the fact that at that time the transmissions were low-speed, and the operating temperature did not exceed 70-90 C. Over time, the power and torques increased, and the original Type A ceased to meet the requirements, since it oxidized at higher temperatures and foamed, unable to withstand high speeds.
The next in the development of ATF was the Type A Suffix A fluid, created in 1957, with improved characteristics. For the first time, additives containing substances based on phosphorus, zinc and sulfur were used in minimal amounts (about 6.2%), which made it possible to improve the antioxidant and other properties of ATF.
After that, for ten years there was nothing new, and only in 1967 did GM take the next step, creating ATF with the index B. From that moment, a classification was introduced under the name DEXTRON, and the liquid was called DEXTRON B. Its fundamental difference was that that a significant amount (about 9%) of substances based on barium, zinc, phosphorus, sulfur, calcium and boron was introduced into its composition, which can be called a package of additives.
The unrestricted chemical extraction of whales pushed them to the brink of extinction, and in 1972 the US government was forced to pass the Law on the Conservation of Endangered Species of Animals and Birds, completely banning whale hunting. Black days have begun for ATF manufacturers. For several years it has not been possible to find a replacement for sperm fat. Using the remaining fluids at the disposal of the manufacturers, the number of automatic transmission failures increased 8 times in the United States, and the case smelled like a disaster. It wasn't until the mid-70s that International Lubricants, in collaboration with renowned organic chemist Philippe, developed a liquid synthetic wax ester called LIQUID WAXESTER, patented under the LXE® trademark, which improved the required ATF properties by an average of 50%. The resulting liquids even began to surpass in a number of characteristics ATF based on spermacet. On the basis of this technology, in 1975 GM created the DEXTRON II C index with an additive content of 10.5%. But it soon became clear that ATF turned out to be quite aggressive and began to cause corrosion of metal surfaces, so a year later DEXTRON II index D was created, into which additional corrosion suppressants were introduced. The next step in 1990 was DEXTRON II index E, which included viscosity stabilizers at low temperatures and stabilizers at high temperatures. The crown of all creations was in 1995 DEXTRON III, which took into account all modern requirements and introduced a complex additive package. So far, GM has created the DEXTRON IV, DEXTRON V and DEXTRON VI. In parallel with GM, in-house developers led a number of firms, such as Ford, which created a number of their own ATFs, united by the MERCON classification, Toyota Tyret classification (DTT).
This led to a fair amount of confusion in the classification of oils and understanding of their compatibility with each other and with the design of the automatic transmission. Therefore, over time, it was decided to tie all these standards to the GM-DEXTRON classification. Therefore, on most ATF packages of any company, you can see the inscription on the back in the annotation: “Analogue DEXTRON III” or “DIV”, etc.
What is the difference in ATF properties from different manufacturers? Determination of compatibility with the automatic transmission design.
I would like to note right away, no matter what worthy experts say, there is no fundamental difference in the properties of the most modern ATFs. If you go into details, then two main factors are taken as the criteria for distinguishing:
- Interaction of ATF with various types of friction materials.
- Various characteristics of the friction coefficients when clutching frictional properties (variable and constant coefficient of friction).
On the first point: There are about a dozen manufacturers of friction materials in the world, such as Borg Warren, Alomatic, Alto and others, each of which develops its own original formulations. The base is usually specially processed cellulose fiber (friction board), to which various synthetic resins are added as a binder, and soot, asbestos, various types of ceramics, bronze chips, fiber composites of the type * and are introduced in various proportions to strengthen and improve the frictional properties carbon fiber. Accordingly, it is believed that the manufacturer of the automatic transmission selects the type of ATF for the friction material used, selecting the optimal value of the shear coefficient between the clutches at full contact in order to minimize heat generation in the clutch packs. However, regardless of the difference in the composition of the clutches, all developers use the same chain, therefore, the high-quality clutches of the native companies do not differ much in properties, therefore they react similarly to different types of ATF.
On the second point: The gearing parameters of the automatic transmission friction elements are determined by the friction coefficient. Friction is, respectively, of two types:
- sliding friction arising from contact of friction elements until they are fully engaged;
- friction at rest, when the clutches come into a state of full engagement and become motionless relative to each other.
In addition to the clutches in the brake and drive elements of the automatic transmission, there is also a torque converter lock-up clutch, which, when changing from a hydrodynamic (due to the compression of fluids between opposite blades) mode of transferring the main torque to a hard one (when the lock is completely pressed against the body and the G / TP works as usual grip on mechanics) gets the same set of friction effects. However, in the H / T of modern automatic transmissions of 6 or more stages, an intermediate mode has appeared, called controlled blocking slip (FLU - Flex Lock Up) for smoother and more comfortable switching, when the pressure regulator supplies and deactivates the pressure controlling the blocking with a high frequency of switching on. keeping it on the verge of slipping. Accordingly, all types of ATF are divided into two classes: with constant friction properties (Type F, Type G) and variable friction properties (DEXTRON, MERCON, MOPAR).
ATF with invariable frictional properties has a fairly linear picture: as the clutch is pressed down (decreasing the slip rate), the friction coefficient increases, and at the moment the clutches engage, it reaches a maximum. This gives the effect of crisp transmissions with minimal matching emphasized.
Accordingly, there is a switching sensation effect. When using ATFs with variable frictional properties at the initial stage of pressing the clutch, the coefficient of friction-sliding has a maximum value, but as they are compressed it slightly decreases, again reaching a maximum at full contact, but at this value the coefficient of resting ectaturation is much lower. This gives the effect of a smoother and more comfortable gear shifting, but the amount of heat generated is increased.
Possible consequences: If you pour ATF with variable properties in an automatic transmission with a hard engagement of g / t, this can cause an undesirable effect of blocking slip. In the case of an unworn automatic transmission, the hydrodynamic transmission will maintain the torque until it is fully engaged and nothing unpleasant will happen. In a worn or damaged automatic transmission with a burnt lock and clutches, excessive sliding can aggravate the situation and cause fatal destruction. If ATF with unchanged frictional properties is poured into an automatic transmission with controlled block slip, this can cause a more rigid engagement of gears, but it will not bring tragic consequences. From this, we can conclude that it is possible to add ATF with modified frictional properties to it, and it will work softer, and if there is a feeling that the automatic transmission is slipping a little more than necessary, you can fill in ATF with unchanged frictional properties and it will work more clearly.
In conclusion, I can add that significantly more serious factors than the frictional properties of oils that affect the operation of automatic transmissions are the temperature regime, the degree of wear of the surfaces of clutches and other devices and control components, frost. Before these factors, the differences in ATF properties become negligible. It makes sense to take them into account only if there are ideal operating conditions for the new car.
The latest development on the ATF market
Several years ago, technologists of the petrochemical company AMALIE MOTOR OIL developed a universal synthetic ATF, which has no analogues in the world, has fantastic properties, which equally satisfies the requirements of automatic transmissions of all types. The fluid was named “Amalie Universal Synthetic Automatic Transmission Fluid”, which revolutionized the US market by being certified by all leading car and automatic transmission manufacturers. A new type of fully synthetic base and an ultra-modern package of multifunctional additives provide unsurpassed protection and stable performance when used in all types of automatic and robotic transmissions, power steering and other hydraulic systems, regardless of manufacturer. It successfully replaces the entire line of DEXTRON, MERCON, Chryster, Toyota, Caterpilar and other transmission fluids. The fluid is recommended for use in highly loaded automatic transmissions of such manufacturers as BMV, Audi, Land Rover, Mercedes, Mitsubishi, Toyota and any other cars of the American, European and Asian markets. This ATF appeared on the Russian market two years ago. For those car owners who have the means and do not spare them for the maintenance of their iron horses, these products are a real solution.
ATF fluid Is a special gear oil that has a liquid consistency and has a mineral or synthetic base. It is intended for vehicles operating on "automatic". ATF transmission fluid is responsible for many functions, for example:
- uninterrupted operation of the gearbox - its control and management;
- cooling and proper lubrication of parts that give in to friction;
- transmission of torque, which passes from the motor to the box through the torque converter;
- ensuring the operation of friction discs.
Many people equate oil with a mixture for automatic transmissions, however, the properties of ATF differ in many parameters. To obtain the correct composition, mineral oils are used, to which special substances are added. If you use extraneous liquids for "automation", then this will surely provoke a breakdown of the gearbox, or its complete failure.
The manufacturer of the first specification of the oil was the automobile concern General Motors. The new mixture entered the mass market in 1949. This was due to the fact that in 1938 the same company developed the first automatic transmission. Subsequently, the carmaker began to work hard on improving the specifications of transmission mixtures and set the strictest requirements for the composition. Since there were no competitors in this market, GM became the specification setter for ATF.
The first types of liquid were made on fat, which was produced from the fat of sea whales. Due to the law prohibiting the hunt for these ocean dwellers, the corporation had to develop a synthetic base.
At the moment, other eminent car brands - Chrysler, Hyundai, Mitsubishi Ford and Toyota - compete with the specifications from General Motors.
Pay particular attention to the packaging of the ATF you are purchasing. Consider the type of oil as well as the specification that suits your transmission.
Types of ATF gear oils
After we have become familiar with what ATF is, we will study all sorts of fluid specifications. The very first of them, as noted above, was published in 1949 thanks to the efforts of General Motors. The common name for the mixture is ATF-A, which was used on all vehicles equipped with "automatic". In 1957 the specification was revised and thus the Type A Suffix A.
So, there are such main types of ATF:
- Mercon - Introduced by Ford in the 80s of the last century. They are as close as possible to other specifications and may be compatible with them. The main differences between the variants from GM and Ford are that the former pays more attention to smoothness of shifting, while the latter to speed;
- Dexron - has been produced by GM since 1968. Since whale oil was used in the manufacture, production had to be suspended. This was also due to poor technical characteristics, as the oil showed poor tolerance to high temperatures. In 1972, Dexron ІІС appears, where jojoba oil served as a basis, which subsequently provoked corrosion of some parts. The next oil, which was equipped with additives that suppress the development of rust, acquired the IID prefix. Fluid with the IIE index was produced until 1993. Its distinguishing feature is the presence of additives that reduce hygroscopic redundancy. The innovation was the release of the type Dexron III (1993). The novelty retained its liquid properties even at very low temperatures, and the frictional characteristics were also improved. In 2005, a new generation appeared with the prefix "VI". An ATF transmission oil was developed for use on the new, which was a 6-range. The mixture has a longer service life as well as a lower kinematic viscosity. The latter parameter improves fuel efficiency;
- Alison C-4 - Developed by General Motors specifically for filling large vehicles - off-road vehicles and trucks.
When to change the transmission mixture?
The ATF must be changed periodically, because this will increase the service life of not only the transmission, but also the car as a whole. Therefore, it is necessary to carry out systematic measurements of the oil level. The replacement period is affected by:
- vehicle mileage;
- operating conditions;
- driving style.
The procedure should be entrusted to specialists at the service station, where there is all the necessary equipment that will allow you to change the oil. After all, you can only drain some of the ATF yourself, a significant part remains in the box. With the help of technical devices, professionals can also wash or replace the filter.
Checking transmission oil in automatic transmission
The long service life of the transmission ensures a timely check of the remaining mixture in the automatic transmission. This operation is carried out in different ways - it all depends on the type of transmission. Before proceeding with the procedure, carefully read the user instructions.
You can check the remaining mixture level on both hot and cold transmissions, because the dipstick has appropriate marks.
If you decide to carry out this operation yourself, then it is worth remembering the need to maintain the exact oil level. In each case, you put the entire system at risk:
- an insufficient level provokes the ingress of air into the pump along with oil (in such a situation, combustion occurs, clutches slip and general system failure). If you find that the level does not reach the desired mark, then try to determine the cause of the oil leak;
- an increased level causes the excess oil to overflow through the breather, the level decreases, therefore, the same problems arise as in the above situation. Ejection through the breather is diagnosed by the degree of contamination of the part with liquid.
How to choose a working fluid according to ATF specification
Each of the groups of oils has different frictional characteristics and temperature differences. What the different ATF specifications mean:
- Dexron IID does not tolerate too cold temperatures, therefore, it is suitable for use only in those countries where the temperature does not fall below -15 degrees during the winter season. Suitable for cars of previous generations;
- Dexron IIE it manifests itself well even at temperatures of -30, it is necessary only in those areas where severe and frequent frosts prevail. The manufacturer guarantees that the liquid will retain its viscosity. Even if your transmission is IID, change it to IIE during the cold season;
- Dexron III applies to literally all modern car models.
An incorrectly selected mixture will provoke multiple malfunctions in the functioning of the automatic transmission. Disc slippage, increase in the time it takes to change gears, jerks at start, etc. are very predictable. All this will be caused by a longer formation of the operating oil pressure. Initially, you may not pay attention to such symptoms, but then they will appear to a greater extent.
Can I mix different types of liquids?
Mixing liquids is permissible, but still it is better not to risk it, because this can lead to breakdown, and a complete replacement of the automatic transmission will pretty much hit your pocket. In order to identify the type of oil, add a special dye to it, which will not affect the characteristics of ATF oils. If it is not possible to determine the specification, then it is better to completely re-fill it.
Long-term use of the same fluid, or the use of a low-quality fake, leads to malfunctions and breakdowns in different engine systems.
Use of ATF
The durability of the transmission depends on maintaining the optimum fluid level. If you know what ATF is, then you also know that oil changes are carried out only in car services under the supervision of specialists.
The fact that something is wrong with the liquid is evidenced by its black or dark brown color. In this case, the appearance of a burnt odor is observed. The oil color of a normally functioning transmission is deep red or red with an orange tint.
As noted above, it is important to avoid fluid overflow. Foaming of the oil provokes its release through the breather. If the level is insufficient, then the pump draws in air. This affects the clutches - the discs begin to slip and burn.
