790019 BridgingtheGap Between DEXRON®-IIand TypeF ATFATF H.E.Deen,R.O'Halloran, E.F.Outten, andJ.P.Szykowski ExxonChemical Co. CURRENTLY TWOMAJOR SPECIFICATIONS dominate theautomatic transmission fluid(ATF) servicefillmarket. TheyaretheDEXRON IIspecification developed byGeneral MotorsandtheM2C33-F (TypeF)specifica tiondeveloped byFord. Themaindif ference between fluidsmeeting these specifications isinfriction character istics. DEXRON-II fluidscontain friction modifier, whereas TypeFfluids donot. Recognizing thisdifference, transmission builders, whohavedesigned theirtrans missions touseonetypeoffluid, recommend againstusingtheother. The purpose ofthispaperistodemonstrate thatDEXRON-II fluids canbeusedin transmissions designed forTypeFATFand toshowthattheDEXRON-II specifica tionprovides agreater safetymarginin termsofoxidation stability thandoesthe TypeFspecification. BACKGROUND ONATFSPECIFICATIONS When Fordofficiallyintroducedthe TypeF ATFspecificationin 1964(1)*,they openeda significantgap inrequirements between themselvesand therestofthe industry.Priorto thattime,the automotiveindustry used fluidsmeetingthe TypeA SuffixA specificationwhich GeneralMotors developed(2). Themostsignificantdifference betweenthe specificationswas thefrictionrequirement.Type F fluid calledfora highstaticcoefficientof friction,while TypeA SuffixA requireda lowstaticcoefficient.Ross and Pearson(3) reportedthat 1964Ford transmissionsoperatedwith fluidshavinga lowstaticcoefficientof friction,i.e., TypeA SuffixA fluids,sufferedclutch plate distress.In addition,they reportedthat fluids meetingthe TypeF specificationwere superiorto TypeA SuffixA fluidsin oxidation stabilityand siliconeseal reversion.In 1968,GeneralMotors introducedthe DEXRON specification(4)which requiredan improvementin oxidationstability;and in1973 they introducedthe DEXRON-IIspec ificationwhich requireda furtherimprovementin oxidationstability(5).Both * Numbersin parenthesisdesignate Referencesat endofpaperABSTRACT An automatictransmissionfluid has been developedwhich can meettheneedsof transmissionsdesigned for eitherfrictionmodifiedor non-frictionmodified fluids. Approved underthe DEXR0N*-IIand M2C138-CJspecifications, it alsomeetsallthe requirementsof theM2C33-F(TypeF) specificationexcept for thefrictionmodifier content. Since useofa frictionmodified fluidin TypeF applicationswould representa radicaldeparturefrom currentrecommendedpractice, data, bothproandcon,ontheconceptare presented.* Registeredtrademark.101 0096-736X/80/8801-0101$02.50Copyright© 1980Societyof AutomotiveEngineers,Inc. Downloaded from SAE International by University of Edinburgh, Saturday, August 25, 2018102 H.E.DEEN,ETAL. specifications calledforafluidhavinga lowstaticcoefficient offriction. Thus, themaindifference between TypeFand DEXRONcontinued tobethefriction prop ertqofthefluid. Latein1975,Fordintroduced anew specification forafactoryfillfluid calledM2C138-CJ(6). Thisfluidisneeded fortheirlarger C-6transmission andhasa lowstaticcoefficient offriction likethe DEXRON-II fluids. ForallotherFord transmissions, TypeFfluidisstill required. Forservicefill,Fordrecom mendsDEXRON-II fluids beusedinthe1977 andsubsequently builtC-6transmissions, whileTypeFisrecommended forallother transmissions. Fordiscurrently redesign ingtherestoftheirtransmissions to permittheuseofM2C138-CJ fluids. Theproblem ofeducating thecar owner,transmission rebuilders, andservice stationpersonnel onthepropertypeof fluidtoaddtoatransmission hasbeen formidable. Ithasbeenmademorecomplex withthemovebyFordtopartial useof DEXRON-II fluids. Recognizing thisprob lem,theSAEinitiated aprogram totryto develop asinglespecification forautomo tiveATF'swhichwouldbeacceptable tothe industry. Thisprogramisnowunderway in acooperative SAE-ASTM study. BRIDGING THEGAPONFRICTION REQUIRE MENTS-TheDEXR0N-II fluids nowonthe marketaremuchdifferent fromtheTypeA Suffix Afluids of1964. Theadditive technology haschangedsignificantly, and thefluidsarenotonlyfarsuperior in ox