790017 Automatic Transmission Fluid Oxidation A Comparison ofShort Term with Long Term Testing Edward J.Friihauf TheLubrizol Corp. Congress andExposition Cobo Hall, Detroit February 26-March 2,1979 SOCIETY OFAUTOMOTIVE ENGINEERS, INC. 400 COMMONWEALTH DRIVE WARRENDALE, PENNSYLVANIA 15096 Downloaded from SAE International by University Of Newcastle, Thursday, August 09, 2018Theappearance ofthecode atthebottom ofthefirstpage ofthispaper indicates SAE's consent thatcopies ofthepaper maybemade forpersonal orinternal use,or forthepersonal orinternal useofspecific clients. Thisconsent isgiven onthecon dition, however, that thecopier paythestated perarticle copy feethrough the Copyright Clearance Center, Inc., Operations Center, P.O. Box765,Schenectady, N.Y. 12301, forcopying beyond thatpermitted bySections 107or108oftheU.S. Copyright Law. This consent does notextend toother kinds ofcopying such as copying forgeneral distribution, foradvertising orpromotional purposes, for creating new collective works, orforresale. Papers published prior to1978 mayalsobecopied ataperpaper feeof$2.50 under theabove stated conditions. SAEroutinely stocks printed papers foraperiod ofthree years following date of publication. Direct your orders toSAE Order Department. Toobtain quantity reprint rates, permission toreprint atechnical paper orper mission tousecopyrighted SAE publications inother works, contact theSAE Publications Division. ISSN 0148-7191 Copyright ©1979 Society ofAutomotive Engineers, Inc. Downloaded from SAE International by University Of Newcastle, Thursday, August 09, 2018790017 Automatic Transmission Fluid Oxidation A Comparison ofShort Term with Long Term Testing Edward J.Friihauf TheLubrizol Corp. ANAUTOMATIC TRANSMISSION FLUID (ATF) performs many functions inanautomatic transmission. These functions arelubrication, power transfer, hydraulic control, cooling, transmission protection, andfriction contribu tions tosmooth shifting. The oxidative and thermal conditions found inmodern automatic transmissions tend todestroy theuseful properties ofATF. Over theyears, thebuilders ofautomatic trans missions andtheformulators ofATF have worked together tominimize theeffects of oxidation onATF performance and, therefore, transmission performance. Avariety ofshort term test methods are used intheUSAtohelp determine howresis tantanATFistooxidation. Chrysler(1)* uses their CBOT (Chrysler Bench Oxidation Test), Ford(2) uses athermal stability test, an8000 cycle cartest andaMercomatic Oxidation Test andGM(3) uses aTHOT (Turbo-Hydra-matic Oxidation Test) andTHCT (Turbo- Hydra-matic Cycling Test). TheCBOT andFord thermal stability test areglassware tests while theTHOT, THCT and Mercomaticinvolve transmissions mounted ontest beds. TheFord 8000 cycle testisacartest. In each test, theATFisdeliberately oxidized under controlled conditions andtheeffects andextent ofATF oxidation aremeasured. Chronologically, new ATFadditives aredeveloped inshort term, high severity oxidation tests andthen longer term oxidation tests arerun. Thelong term tests usually involve vehicles ontheroad while theshort term tests usually involve transmission or transmission components mounted ontest beds. One intent ofthis paper istocompare theextent ofATF oxidation inshort term tests tothat inlong term tests. Toaccomplish this, long term taxicab data will becompared with short term bench transmission test data. Avariety ofoiltests areavailable to measure theextent ofATFoxidatlon(4). These tests include viscosity change, change inacid orbase number, insolubles content, *Numbers inparentheses designate References attheendofthepaper ABSTRACT The extent ofautomatic transmission fluid oxidation iscompared forshort term bench transmission tests with long term vehicle tests .Thetechnique ofBlotter SpotAnalysis isemphasized forthecomparison. Blotter Spot Analyses canhelp decide when anautomatic transmission fluid should be changed insevere service. 0148-7191/79/0226-0017$02.50 Copyright ©