Dexron is the new General Motors trademark which identifies currently recommended service automatic transmission fluids. The minimum quality of these fluids is higher than that of the formerly used Type A Automatic Transmission Fluids. The new fluids will provide improved transmission operation, both initially and for extended periods of service. They may be used in servicing not only current transmission and power steering units, but also all older units for which Type A fluids were originally recommended.The fluids were developed principally to achieve longer shift-time retention and clutch plate durability. Advances were also made in respect to low temperature fluidity, antifoam quality, fluid-seal compatibility, oxidation resistance, and fluid-nylon compatability. This paper reviews the development of the Dexron-quality fluids, and outlines the recently established specification requirements and qaulification procedures which are used to define this higher quality level for fluids supplied to the service fluid market.