Cutaway view of ZF automatic transmission. Photo by Ben Jeffrey.
Just as vehicle manufacturer recommendations for engine oil are changing at an ever-increasing pace, so, too, are requirements for the the ever-widening range of automatic transmission fluids. With the advent of overdrive transmissions and 4,5,6 or more speed units being used in today’s cars, it is important to use the correct fluid, changed at recommended intervals, to insure your transmission will last as long as your engine and also keep your vehicle’s drivetrain warranty in effect. Now that 10W30 and 10W40 engine oils are considered antiquated by most standards, ATF basic fluids such as Dexron and Ford Type F are also falling by the wayside as the old standbys. Many manufacturers are still producing their own transmissions, but they are also getting their assembled transmissions from other sources for certain models and engine sizes. This means that there is not one standard fluid for GMs, or Fords, or Chryslers any longer. Imported car automatics can produce even more problems, because of their requirements for both viscosity and oxidation inhibitors.
When automatic transmissions first appeared in standard production models in the early fifties, they used common engine or gear oil. As the transmissions themselves were refined, they began using Type A fluid in the late fifties. Type A evolved into Type A Suffix A and then into Dexron, however, each of these iterations relied on a sperm whale oil additive to act as a friction modifier, at least until the use of whale oil was outlawed in the early seventies. Dexron II became the original equipment transmission oil in 1972, but the manufacturer encountered problems with corrosion to the solder joints in the transmission oil cooler and added a corrosion inhibitor in 1975; the new fluid was called Dexron II-D. This was later reformulated to Dexron II-E when another additive was included to reduce water absorption. All GM vehicles used Dexron II-E and it supersedes any previous recommendations for Type A, Type A Suffix A, and any of the previous Dexron requirements.
Dexron III became the new GM standard in 1993 and was used in all cars and light trucks (except Saturn) until 2006. It was obsoleted in favor of Dexron III-H. Also in 2006, GM first introduced Dexron VI, which is a synthetic blend-based fluid and was used in all 6-speed transmissions but can be retrofitted to any previous fluid specifications and can be mixed with the older mineral-based fluids. Dexron VI is also found in BMWs that came with the GM 6-speed transmissions. It is not recommend for Pontiac Vibe, Chevrolet Aveo or Saturn Ion transmissions as these were not produced by General Motors. Neither is it recommended for any cars equipped with continuously variable transmissions, commonly known as CVTs.
Ford first produced their own transmission fluid formulation in 1967, referred to as Type F or Type FA. The name comes from Ford’s specification number for the fluid, ESW M2C33-F. This fluid was used in all Ford transmissions until 1977 and most Ford transmissions until 1980.
The development of the C5 transmission in 1981 brought a new specification called Type H named after the specification ESP M2C166-H. About the same time, Ford C6 transmissions upgraded to a new formulation, ESW M2C138-CJ or Type CJ. These transmissions cannot use Type F/FA; however, Dexron II could be substituted. Type H eventually was reformulated and received anti-shudder additives; it was then renamed Mercon and it was an acceptable retrofit for both Type H and Type CJ and became the new Ford standard fluid from 1987-2007. Mercon V was introduced in 2008 and supersedes any requirements for H, CJ or Mercon. It does not replace Type F or Type FA but is often marketed in retail establishments now as Dexron III/Mercon V and takes the place of any previous non-Type F/FA requirements. Mercon SP was prevalent in 2005-2007 6-speed automatics and has additional additives over Mercon V; however, SP can be substituted in any Mercon V recommendation. Ford also produced their own Mercon CVT fluid from 2005-2007, however, all aftermarket CVT-specific fluids meet the Ford requirement, no matter who the manufacturer.
The year 2008 saw the release of Mercon LV, a synthetic-based fluid that is not compatible with any previous Mercon specifications. Transmissions requiring LV include the rear wheel drive Ford 5R110 Torque Shift and 4R75/WE transmissions, as well as the front wheel drive 4F27E, AW ECVT, 6F50/55N and the 6F35N.
Early Chrysler transmissions also used Type A fluid until the introduction of Dexron, and continued to use Dexron II and III in rear-wheel drive transmissions until 1997. AMC also used the Chrysler Torque Flight (Torque Command) transmissions throughout the sixties and seventies, so AMC’s fluid requirements were the same as the early Chryslers. In 1997, ATF+2 was introduced with additional additives for 3-speed automatics and ATF+3 was released for 4-speed automatics. By 1998, both were gone in favor of the new synthetic-based ATF+4. This synthetic fluid can be retrofit into any previous Chrysler transmission, but it cannot be mixed with Dexron or Mercon fluids; a complete change would be necessary, including a system flush and draining of the torque converter. ATF+4 was used in all 1998 and newer Chryslers, except minivans with the 41TE/AE transmissions until 2002, when Chrysler ATF+5 synthetic fluid was released.
You can see how confusing it gets; we just mentioned 21 different fluids for American cars alone. There are at least a dozen additional specifications for European and Japanese vehicles, which we will discuss next week. Meanwhile, we strongly recommend that you check your transmission dipstick or the vehicle owner’s manual to see which of these 21 specifications your car requires. Check with your local dealership’s service department, if you have to, and do not stray from their recommendation, or its acceptable equivalent, to be sure your automatic transmission is operating at peak efficiency and receiving the proper lubrication and additive protection needed to extend its life.
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