SA E TECHNICAL PA PER SERIES The Oxidation Stability of General Motors Proposed Factory-Fill Automatic Transmission Fluid Steven P. Kemp General Motors Powertrain James L. Linden General Motors Research and Environmental Staff Reprinted from: Passenger Car Engine Lubricants (SP-939) The Engineering Society *A =For Advancing Mobility and sea ~ir and space, International Fuels and Lubricants Meeting and Exposition San Francisco, California October 19-22,1992 400 COMMONWEALTH DRIVE, WARRENDALE, PA 15096-0001 U.S.A. Downloaded from SAE International by University of Birmingham, Monday, August 20, 2018The appearance of the ISSN code at the bottom of this page indicates SAE's consent that copies of the paper may be made for personal or internal use of specific clients. Thisconsent is given on thecondition, however, that the copier pay a $5.00 per article copy fee through the Copyright Clearance Center, Inc. Operations Center, 27 Congress St., Salem, MA 01 970 for copying beyond that permitted by Sections 107 or 108 of the U.S. Copyright Law. This consent does not extend to other kinds of copying such as copying for general distribution, for advertising or promotional purposes, for creating new collective works, or for resale. SAE routinely stocks printed papers for a period of three years following date of publication. Direct your orders to SAE Customer Service Department. To obtain quantity reprint rates, permission to reprint a technical paper or permission to use copyrighted SAE publications in other works, contact the SAE Publications Group. All SAE papers, standards, and selected books are abstracted and indexed in the SAE Global Mobility Database. No part of this publication may by reproduced in any form, in an electronic retrieval system or otherwise, without the prior written permission of the publisher. ISSN 0148-7191 Copyright 1992 Society of Automotive Engineers, Inc. Positions and opinions advanced in this paper are those of the author(s) and not necessarily those of SAE. The author is solely responsible for the content of the paper. A process is available by which discussions will be printed with the paper if it is published in SAE transactions. For permission to publish this paper in full or in part, contact the SAE Publications Division. Persons wishing to submit papers to be considered for presentation or publication through SAE should send the manuscript or a 300 word abstract of a proposed manuscript to: Secretary, Engineering Activity Board, SAE. Printed in USA Downloaded from SAE International by University of Birmingham, Monday, August 20, 2018The Oxidation Stability of General Motors Proposed Factory-Fill Automatic ~ransmission Fluid Steven P. Kemp General Motors Powertrain James L. Linden General Motors Research and Environmental Staff ABSTRACT Using standard industry tests, the oxidation stability of General Motors current factory-fill automatic transmission fluid (ATF) was compared to that of a proposed factory-fill ATF to be introduced for the 1995 Model Year. Full-scale transmission tests and Aluminum Beaker Oxidation Tests run at various temperatures showed that a proposed factory-fill fluid is substantially more resistant to oxidation than the current factory-fill ATF. Using Total Acid Number increase (A-TAN) as the measure of oxidation, a minimum of 35% improvement was obtained with a proposed factory-fill. This improvement at least doubles the time to "perceived fluid failure" (A-TAN = 2.5). OXIDATION IS THE CHEMICAL reaction of a substance with oxygen and is a major cause of automatic transmission fluid failure. The oxidation process involves the formation of free radicals, acidic compounds, and polar compounds which attack and degrade the ATF additive package (especially friction and viscosity modifiers), the ATF base oil, transmission elastomer compounds, copper alloy components, and other sensitive transmission parts. In