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Automatic transmission fluid

From Wikipedia, the free encyclopedia
For the transmission lubricant, see gear oil.
Automatic transmission fluid

Automatic transmission fluid (ATF) is a hydraulic fluid that is essential for the proper functioning of vehicles equipped with automatic transmissions. Usually, it is coloured red or green to differentiate it from motor oil and other fluids in the vehicle.

This fluid is designed to meet the unique demands of an automatic transmission. It is formulated to ensure smooth valve operation, minimize brake band friction, facilitate torque converter function, and provide effective gear lubrication.

ATF is commonly utilized as a hydraulic fluid in certain power steering systems, as a lubricant in select 4WD transfer cases, and in modern manual transmissions.

Modern use

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Modern ATF consists of a base oil and an additive package that contains a wide variety of chemical compounds intended to provide the required properties of a particular ATF specification. Most ATFs contain some combination of additives that improve lubricating qualities,[1][2][3] such as anti-wear additives, rust and corrosion inhibitors, detergents, dispersants and surfactants (which protect and clean metal surfaces); kinematic viscosity and viscosity index improvers and modifiers, seal swell additives and agents (which extend the rotational speed range and temperature range of the additives' application); anti-foam additives and anti-oxidation compounds to inhibit oxidation and "boil-off"[4] (which extends the life of the additives' application); cold-flow improvers, high-temperature thickeners, gasket conditioners, pour point depressant and petroleum dye.[citation needed] All ATFs contain friction modifiers, except for those ATFs specified for some Ford transmissions and the John Deere J-21A specification;[5] the Ford ESP (or ESW) - M2C-33 F specification Type F ATF (Ford-O-Matic) and Ford ESP (or ESW) - M2C-33 G specification Type G ATF (1980s Ford Europe and Japan)[2] specifically excludes the addition of friction modifiers.[2] According to the same oil distributor, the M2C-33 G specification requires fluids which provide improved shear resistance and oxidation protection, better low-temperature fluidity, better EP (extreme pressure) properties and additional seal tests over and above M2C-33 F quality fluids.[citation needed]

The friction modifier means that the fluid sticks to the surface of the metal slightly stronger, and therefore only helps to prevent early wear. It would be required for Ford and BorgWarner to prove that their transmissions are somehow harmed by friction modifiers. In many countries, Ford has said that the modern Dex3 fluid is fine for the same transmissions that it says require the older standard.[citation needed]

There are many specifications for ATF, such as the General Motors (GM) DEXRON and the Ford MERCON series, and the vehicle manufacturer will identify the ATF specification appropriate for each vehicle. The vehicle's owner's manual will typically list the ATF specification(s) that are recommended by the manufacturer.

Automatic transmission fluids have many performance-enhancing chemicals added to the fluid to meet the demands of each transmission.[citation needed] Some ATF specifications are open to competing brands, such as the common DEXRON specification, where different manufacturers use different chemicals to meet the same performance specification. These products are sold under license from the OEM responsible for establishing the specification. Some vehicle manufacturers will require "genuine" or Original Equipment Manufacturer (OEM) ATF. Most ATF formulations are open 3rd party licensing and certification by the automobile manufacturer.

Current fluids

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2014 Ford Mercon ULV and ACDelco Dexron-ULV ATF

Synthetic ATF is available in modern OEM and aftermarket brands, offering better performance and service life for certain applications (such as frequent trailer towing).

Oil pan of an automatic transmission with sedimented wear

Using a lint-free white rag to wipe the dipstick on automatic transmissions is advised so that the color of the fluid can be checked. Dark brown or black ATF can be an indicator of a transmission problem, vehicle abuse, or fluid that has far exceeded its useful life. Overused ATF often has reduced lubrication properties and abrasive friction materials (from clutches and brake bands) suspended in it; failure to replace such fluid will accelerate transmission wear and could eventually ruin an otherwise healthy transmission. However, color alone is not a completely reliable indication of the service life of ATF, as most ATF products will darken with use. The manufacturer's recommended service interval is a more reliable measure of ATF life. In the absence of service or repair records, fluid color is a common means of gauging ATF service life.

CVTs and dual-clutch transmissions often use specialized fluids. Transfer cases and differentials in four-wheel-drive/all-wheel-drive vehicles sometimes require specialized fluids, such as Honda Dual Pump-II, Honda VTM-4, and Jeep Quadra-Trac.

History

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1940 GM Hydra-Matic Automatic Transmission Fluid

The history of automatic transmission fluids parallels the history of automatic transmission technology. The world's first mass-produced automatic transmission, the Hydra-Matic 4-speed, was developed by General Motors (GM) for the 1940 model year. The Hydra-Matic transmission required a special lubricant GM called Transmission Fluid No. 1. for the Hydra-Matic Drive. This transmission fluid was only available at Oldsmobile, Pontiac, and Cadillac dealerships. As technology advanced and OEMs demanded longer-lasting and higher-quality automatic transmissions, so too did automatic transmission fluids advance.

In 1949, GM released a new Type "A" fluid specification.[9][10] In an attempt to make GM automatic transmission fluid available at retailers and service garages everywhere. Every automatic transmission produced by any vehicle manufacturer used GM Type "A" transmission fluids in their transmissions from 1949-1958.

1960 Ford Type B ATF

In 1959, Ford began releasing their own automatic transmission fluid specifications; see MERCON for more information. From 1958-1968 many vehicle manufacturers continued to use the next GM automatic transmission fluid specification, the Type "A" Suffix "A" fluid, in their transmissions. In 1966, Chrysler began releasing their own automatic transmission fluid specifications; see Mopar ATF for more information. GM ATF was the same color as engine oil through 1967. Aftermarket ATF was available with red dye as an aid in fluid leak detection. Dexron (B) was the first GM ATF to require red dye.[citation needed]

From the 1940s through the early 1970s, ATF contained whale oil as a rust and corrosion inhibitor.[11] A moratorium on whale oil at that time prevented the continued production of older ATF such as the original 1967 DEXRON formulation (Type B), and the fluids which preceded it. Vintage GM (1940-1967), Ford (1951-1967, and Chrysler products (1953-1966) used GM Type A fluid or GM Type A Suffix A fluids; these fluids are no longer produced. GM recommends Dexron-VI fluid, Ford recommends Mercon V fluid, and Chrysler recommends ATF+4 fluids for vintage transmission use.

Through the late 1970s, Ford transmissions were factory-filled with a fluid identified as ESW M2C33-F. To provide a fluid that would be available to the general public for service fill, oil companies and other factory fill suppliers were allowed to develop fluids meeting the ESW M2C33-F specification and market these fluids under their brand names but identified as Type F.

1954 Mopar Type A ATF

The second generation of transmission fluid was released in 1974 as the factory fill specification, ESW M2C138-CJ. This fluid was developed to modify the vehicle shifting characteristics and to provide considerable improvement in the oxidation resistance and anti-wear performance.

No service fluids were developed and for a short time, DEXRON fluids approved by General Motors were considered acceptable. With continuing changes and improvements in transmission design, a centrifugal lock-up torque converter clutch was introduced into the C5 transmission to smooth engine vibrations sensed by the occupant of the vehicle. An associated shudder problem forced the introduction of the factory fill specification ESP M2C166-H. Servicing transmissions with DEXRON fluids was unacceptable since not all DEXRON fluids were capable of eliminating the shudder phenomenon. The fluids that could be used were a subset of the DEXRON fluids. The advent of Type H as factory fill necessitated the development of a service fluid specification to match the performance expected from Type H. This resulted in the release of the MERCON specification in 1987.[12]

1988 Toyota Type T ATF

One major revision occurred in September 1992, when low-temperature viscosity requirements, volatility requirements, viscosity change limits after high-temperature exposure and improved oxidation limits were introduced. These changes raised the performance of MERCON fluids above ESP M2C166-H levels.

The development of modulating and continuous slipping clutch converters has prompted the need to develop the MERCON V specification. Included are requirements to verify the anti-wear capabilities and anti-shudder characteristics of the fluid.

The MERCON V specification was further modified sometime before 2007 to make it backwards-compatible with MERCON. Ford has/is terminating all license agreements for the manufacture and sale of MERCON in favor of MERCON V.[13]

Toyota continued using GM ATF, including Dexron (B) and Dexron-II(D) in most of their automatic transmissions until 2003. In 1988, Toyota began releasing its own automatic transmission fluid specifications, see Toyota ATF for more information.

"Lifetime" fluids

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In 1967, Ford produced the Type-F fluid specification. The Type-F specification was intended to produce a "lifetime" fluid which would never need to be changed.[citation needed] This was the first of many Ford "lifetime" fluids. The 1974 Ford Car Shop Manual reads "The automatic transmission is filled at the factory with "lifetime" fluid. If it is necessary to add or replace fluid, use only fluids which meet Ford Specification M2C33F. Many other transmission manufacturers have followed with their own "Lifetime" automatic transmission fluids".

How ATF Can Last a "Lifetime"

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To understand how a fluid can last a "lifetime", a study of the 1939 Chrysler Fluid Drive Fluid is helpful. The lesson learned by Chrysler with its fluid drives applies to modern automatic transmissions as well.[14] The November 1954 edition of Lubrication Magazine (Published by The Texas Company, later known as Texaco) featured a story called "Evolution of the Chrysler PowerFlite Automatic Transmission." This article described the fluid used in the 1939 Chrysler Fluid Drive and its subsequent revisions and enhancements through 1954.

The fluid drive fluid coupling is partially filled with Mopar Fluid Drive Fluid, a special highly refined straight mineral oil with a viscosity of about 185 SUS at 100°F., excellent inherent oxidation stability, high viscosity index (100), excellent ability to rapidly reject air, very low natural pour point (-25°F.), ability to adequately lubricate the pilot ball bearing and seal surface, and neutrality towards the seal bellows.

The fluid operates under almost ideal conditions in what is essentially a hermetically sealed case; the small amount of atmospheric oxygen initially present is removed by a harmless reaction with the fluid to leave a residual inert (nitrogen) atmosphere. As a consequence, it has not been necessary to drain and replace the fluid, and the level-check recommendation has been successively extended from the original 2,500 miles to 15,500 miles and finally to "never" - or the life of the car.

Since drains and level checks were not only unnecessary but frequently harmful (through the introduction of more air, and seal-destroying dirt), Chrysler eventually left off the tempting level inspection plugs. This mechanism is, therefore, one of the very few that are lubricated for the life of the car. There are now myriad examples of couplings that have operated well over 100,000 miles without any attention whatsoever and were still in perfect condition when the car was retired.

On European-type cars, a "Lifetime" means 180,000 km or 112,000 miles as the lifetime of a vehicle or transmission. Service intervals of newer type cars are from 80,000 to 120,000 km which equals 50,000 to 75,000 miles. Flushing or refilling the fluid on lifetime-filled transmissions requires the use of equipment to fill from below, engaging the transmission torque converter or using an external pump.[15][16][17][18]

Sealed Transmissions

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Umbrella style transmission breather to prevent water ingestion

Any automatic transmission fluid will last longer if the transmission case can be hermetically sealed, but transmissions typically have two potential entry points for air:

  1. The Dipstick Tube. Any transmission with a dipstick tube has the potential to let additional oxygen into the transmission through a dipstick that is not fully seated in the tube or a dipstick tube plug that is not fully seated. Even the process of checking the fluid level with a dipstick can allow additional oxygen and dirt to be transmitted. Many modern transmissions do not have a dipstick. They have sealed transmission fluid level check plugs instead. By removing the traditional dipstick, the transmission manufacturer has also removed a potential entry point for oxygen; this reduces the potential for fluid oxidation. A sealed transmission will typically have a longer transmission fluid life than a non-sealed transmission.
  2. The Transmission Vent. Transmissions need vents to compensate for internal air pressure changes that occur with fluctuating fluid temperatures and fluctuating fluid levels during transmission operation. Without those vents, pressure could build resulting in seal and gasket leaks. Before the use of better quality base oil in ATF in the late 1990s, some older transmission breather vents contained a Transmission Air Breathing Suppressor (TABS) valve to prevent oxygen and water ingestion into their transmissions.[19] Oxygen reacts with high-temperature transmission fluid and can cause oxidation, rust, and corrosion. Automatic transmission fluids using lower quality base oil oxidized more easily than fluids using higher quality base oils.[20] Transmission manufacturers now use smaller, remote mounted, breather vents specially designed to keep out water, but allow a small amount of air movement through the breather as necessary.[21]

Sealed ATF Containers

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Any automatic transmission fluid will last longer if it comes from an unopened container. Experts advise that containers storing automatic transmission fluid (ATF) be sealed; if exposed to the atmosphere, ATF may absorb moisture and potentially cause shift concerns. Experts have also advised that, when performing repairs on ATF-equipped transmissions, fresh ATF be used when refilling the transmission, and have warned not to reuse ATF.

Example Maintenance Schedule

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Base Stock Oil Categories for Ford ATF based upon timeline of availability vs. fluid life under "Normal" driving
API BaseStock Oil Miles
1949 Group 1
 
 5,000
1950 Group 1
 
 10,000
1959 Group 1
 
 15,000
1959 Group 1
 
 15,000
1960 Group 1
 
 15,000
1967 Group 1*
 
 30,000
1972 Group 1*
 
 30,000
1974 Group 1*
 
 30,000
1981 Group 1*
 
 30,000
1987 Group 1*
 
 30,000
1996 Group 2+
 
 100,000
2001 Group 3
 
 150,000
2014 Group 3+
 
 150,000
*Hydrotreated Group 1

Lifetime automatic transmission fluids made from higher-quality base oil and an additive package are more chemically stable, less reactive, and do not experience oxidation as easily as lower-quality fluids made from lower-quality base oil and an additive package. Therefore, higher-quality transmission fluids can last a long time in normal driving conditions (Typically 100,000 miles (160,000 km) or more).

The definition of 'Lifetime Fluid" differs from transmission manufacturer to transmission manufacturer. Always consult the vehicle maintenance guide for the proper service interval for the fluid in your transmission and your driving conditions.

Chevrolet Colorado Example: According to the Scheduled Maintenance Guide a 2018 Chevrolet Colorado with "Lifetime Fluid" could have two different fluid service intervals depending upon how the vehicle is driven:[22]

1. Normal Driving

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  • Carry passengers and cargo within recommended limits on the Tire and Loading Information label
  • Driven on reasonable road surfaces within legal driving limits.

2. Severe Driving

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  • Mainly driven in heavy city traffic in hot weather
  • Mainly driven in hilly or mountainous terrain
  • Frequently towing a trailer
  • Used for high-speed or competitive driving
  • Used for taxi, police, or delivery service.

Under "Severe" driving conditions, replace automatic transmission fluid and filter every 45,000 mi (72,420 km)

Aftermarket Automatic Transmission Fluids

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1976 Licensed Mobil Dexron II(D) for GM, Chrysler, and AMC Vehicles

For over 70 years, the oil aftermarket has produced both licensed and non-licensed, formulations of automatic transmission fluids (ATF).[23][24] Today, aftermarket fluids asserted by their manufacturers to be compatible for use in various brands of automatic transmissions continue to be sold under names such as Multi-Purpose and Multi-Vehicle fluids. Non-licensed fluids are typically less expensive; these fluids are not regulated or endorsed by the vehicle manufacturer for use in their transmissions. Vehicle manufacturer-approved and licensed fluids must have the license number printed on the product information label of the container or the container housing. Non-licensed fluids do not show a license number. Make sure the fluid to be installed into a transmission matches the recommended fluid in the specifications section of the vehicle's owner's manual.

Note that: If your vehicle is still under warranty, you should only use OEM fluids. Otherwise, your dealer might void it.[25]

Mislabeled or Misleading Labeling on ATF Containers

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ATF which has been mislabeled, has misleading labeling, or is fraudulently bottled as another product is an ongoing problem. Some of these fluids have led to multiple transmission failures.[26] The three organizations shown below are trying to stop this problem in the United States.

  1. United States Laws: The U.S. Department of Commerce, National Institute of Standards and Technology (NIST), Handbook 130 2019 Edition, contains Uniform Laws and Regulations in the Areas of Legal Metrology and Fuel Quality. Section IV.G.3.14 defines laws regulating the Labeling and Identification of Transmission Fluid.[27] Paragraph IV.G.3.14.1.1. Container Labeling. reads The label on a container of transmission fluid shall not contain any information that is false or misleading.
  2. California Laws: The State of California has developed additional Laws in an attempt to prevent mislabeled and misleading labelling. Statutes: California Business and Professions Code, Division 5, Chapters 6, 14, 14.5, and 15.[28] Regulations: California Code of Regulation, Title 4, Division 9, Chapters 6 and 7.[29]
  3. American Petroleum Institute (API) Monitoring: The American Petroleum Institute (API) maintains a list of invalid labelling of petroleum products. This real-time list includes motor oils and ATF.[30]

See also

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References

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  1. ^ "Automatic Transmission Fluid Additives - Driveline Additives - the Lubrizol Corporation". Archived from the original on 19 April 2012. Retrieved 18 April 2012.
  2. ^ a b c "BP" (PDF). bp.com. Archived from the original (PDF) on 31 March 2010. Retrieved 9 June 2012.
  3. ^ What is Synthetic Oil Made Of?. gjjhawk. 11 June 2009. Archived from the original on 9 December 2016. Retrieved 26 October 2021 – via YouTube.
  4. ^ "Answers - The Most Trusted Place for Answering Life's Questions". Answers.com. Archived from the original on 30 November 2012. Retrieved 18 June 2012.
  5. ^ "BP" (PDF). bp.com.[permanent dead link‍]
  6. ^ "Chrysler LLC ATF+4Ž Info Center". Centerforqa.com. Archived from the original on 1 March 2012. Retrieved 28 February 2012.
  7. ^ "Ford Motorcraft Automatic Transmission Fluid Chart" (PDF). Ford Motor Company. Archived from the original (PDF) on 11 October 2016. Retrieved 14 October 2016.
  8. ^ "Honda ATF DW-1 Equivalent". Oils Advisor. Archived from the original on 18 May 2024. Retrieved 14 May 2024.
  9. ^ Hunstad, N.A.; Selby, T.W.; Osborne, R.E. (1 January 1956). "The Present Status of Automatic Transmission Fluid, Type A". SAE Technical Paper. SAE Technical Paper Series. 1. doi:10.4271/560225. eISSN 2688-3627. ISSN 0148-7191 – via SAE International.
  10. ^ Kelley, Oliver K. (1 January 1949). "Is The Torque Converter Going To Be "It"?". SAE Technical Paper. SAE Technical Paper Series. 1. doi:10.4271/490011. eISSN 2688-3627. ISSN 0148-7191 – via SAE International.
  11. ^ "Transmission Problems in Cars Linked to Ban on Whale Killing". The New York Times. 17 April 1975. p. 32. Archived from the original on 29 February 2024. Retrieved 29 February 2024.
  12. ^ "A brief history of automatic transmission service fluid" Revised and effective 1 January 1999 Ford Motor.
  13. ^ "LUBE REPORT: Ford Pulls the Plug on Mercon". Archived from the original on 6 October 2014. Retrieved 22 April 2012.
  14. ^ "Evolution of the Chrysler PowerFlite Automatic Transmission". Lubrication. Vol. 40, no. 11. New York, NY: The Texas Company. November 1954 [1954]. pp. 129–135.
  15. ^ Getriebe-Service! SO wichtig sind Getriebespülung und Ölwechsel fürs Automatikgetriebe. Die Autodoktoren - offizieller Kanal. 29 March 2019. Archived from the original on 27 April 2021. Retrieved 26 October 2021 – via YouTube.
  16. ^ 1 Tag in Holgers Werkstatt - Teil 2 | Billigteile im Fiesta sorgen für Gefahr. Die Autodoktoren - offizieller Kanal. 10 November 2017. Archived from the original on 27 April 2021. Retrieved 26 October 2021 – via YouTube.
  17. ^ Riesenproblem durch Verkokung im GTI-Motor | Wasser im Tigra und ein ruckelnder A4. Die Autodoktoren - offizieller Kanal. 26 January 2018. Archived from the original on 27 April 2021. Retrieved 26 October 2021 – via YouTube.
  18. ^ More times described experience by leading masters of automotive service business which are recognized as instructors and masters of the Cologne guild, but also work as infuencers of their business.
  19. ^ US5129422A, Jr, Ellard D. Davison & Rabhi, Lounes, "Transmission breather control valve", issued 1992-07-14  Archived 26 April 2021 at the Wayback Machine
  20. ^ Davison, E. D.; Haviland, M. L. (1 February 1974). Transmission Air Breathing Suppressor (TABS) Valve - A Device for Improving Automatic Transmission Fluid Life (Report). Warrendale, PA: SAE Technical Paper. Archived from the original on 28 January 2019. Retrieved 6 February 2019.
  21. ^ US20110173935A1, Tesner, Kenneth C.; Vo, Hoang L. & Cattell, Dale, "Transmission breather assembly", issued 2011-07-21  Archived 27 April 2021 at the Wayback Machine
  22. ^ https://my.chevrolet.com/learn/2018/Colorado Archived 28 September 2020 at the Wayback Machine Learn about my 2018 Chevrolet Colorado
  23. ^ GM Automatic Transmission Fluid - ATF History Part 2. WeberAuto. 14 October 2018. Archived from the original on 17 May 2021. Retrieved 26 October 2021 – via YouTube.
  24. ^ https://www.api.org/products-and-services/engine-oil/unauthorized-use-of-api-certification-marks%7CUnauthorized Use of API Certification Marks Archived 26 April 2019 at the Wayback Machine
  25. ^ "Honda ATF DW-1 Equivalent". Oils Advisor. Archived from the original on 18 May 2024. Retrieved 14 May 2024.
  26. ^ Morrison, Allan (18 April 2019). "California Department of Food and Agriculture Division of Measurement Standards Petroleum Products Program Fuels and Lubricants Laboratory Update on Activities - BAR Advisory Group Meeting" (PDF). California Bureau of Automotive Repair.
  27. ^ "Archived copy" (PDF). Archived from the original (PDF) on 4 December 2019. Retrieved 5 December 2019.{{cite web}}: CS1 maint: archived copy as title (link)
  28. ^ "Extracts from the CALIFORNIA BUSINESS AND PROFESSIONS CODE DIVISION 5 - WEIGHTS AND MEASURES In the Areas of Weights and Measures, and Fuels, Lubricants and Automotive Products - CHAPTER 14.5. - Service Stations §§13650-13660" (PDF). California Department of Food and Agriculture. January 2019. Archived (PDF) from the original on 23 February 2019. Retrieved 3 December 2019.
  29. ^ "Browse - California Code of Regulations".
  30. ^ "API Monogram & APIQR Non-Licensee/Registrant List". Archived from the original on 3 December 2019. Retrieved 3 December 2019.
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