Automatic Transmission Fluid - History

History

In the 1950s, 1960s, and 1970s, ATF contained whale oil as a friction modifier. But since whale oil would break down at higher temperatures, cars produced in the 1970s and later would not be able to use whale oil because of the higher engine coolant temperatures employed to reduce emissions and save fuel. A moratorium on whale oil at that time prevented the continued production of older ATF such as the original DEXRON formulation (Type B), and the Type A which preceded it. General Motors began marketing Dexron II Type C and later Dexron II Type D to replace the fluids which were made from whale oil.

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 than factory fill suppliers were allowed to develop fluids meeting the ESW M2C33-F specification and market these fluids under their own brand names but identified as Type F. A 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 eliminated 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 V specification in 1987.

The MERCON specification requires information on the following:

• Color
• Miscibility with factory fill fluids
• Viscosity at -40C, -20 C, 0 C and 100 C.
• Flash point
• Copper strip behavior.
• Shift feel with Ford Taurus transmission.
• Anti-foaming Characteristics
• Elastomer compatibility
• Friction Characterization
• Oxidation behavior at 155 C
• Transmission cycling
• Vane Pump
• Wear tests

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 some time prior to 2007 to make it backward compatible with Mercon. Ford has / is terminating all license agreements for the manufacture and sale of Mercon in favor of Mercon V. See http://www.imakenews.com/lng/e_article000564317.cfm?x=b79gdNq,b2W5q9fm,w for additional details.