400 Commonwealth Drive, Warrendale, PA 15096-0001 U.S.A. Tel: (724) 776-4841 Fax: (724) 776-5760 Web: www.sae.org SAE TECHNICAL PAPER SERIES2005-01-3891 Investigation of Failure Modes in the DEXRON® III-H GM Cycling and Oxidation Tests R.E. Baren, M.T. Devlin, S.H. Tersigni and T.C. Jao Afton Chemical Corporation Powertrain & Fluid Systems Conference and Exhibition San Antonio, Texas USA October 24-27, 2005Downloaded from SAE International by University of British Columbia, Sunday, July 29, 2018By mandate of the Engin eering Meetings Board, th is paper has been approved for SAE publication upon completion of a peer review process by a minimum of three (3) industry experts under the supervision of the session organizer. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise,without the prior written permission of SAE. For permission and licensing requests contact: SAE Permissions 400 Commonwealth DriveWarrendale, PA 15096-0001-USAEmail: [email protected]: 724-776-3036Tel: 724-772-4028 For multiple print copies contact: SAE Customer ServiceTel: 877-606-7323 (inside USA and Canada)Tel: 724-776-4970 (outside USA)Fax: 724-776-1615Email: Customer [email protected] ISSN 0148-7191Copyright © 2005 SAE InternationalPositions 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 pap er if it is publishe d in SAE Transactions. Persons wishing to submit papers to be considered for presentation or publication by SAE should send themanuscript or a 300 word abstract of a proposed manuscript to: Secretary, Engineering Meetings Board, SAE. Printed in USADownloaded from SAE International by University of British Columbia, Sunday, July 29, 20182005-01-3891 Investigation of Failure Modes in the DEXRON® III-H GM Cycling and Oxidation Tests R.E. Baren, M.T. Devlin, S.H. Tersigni and T.C. Jao Afton Chemical Corporation Copyright © 2005 SAE International ABSTRACT To develop an automatic transmission fluid (ATF) that meets DEXRON® III-H specifications, the ATF must pass two critical tests, the GM oxidation test (GMOT) and the GM cycling test (GMCT), in addition to many other performance tests. The specification on the GMOT is that delta TAN (difference in total acid number compared with the fresh oil) at the end of the test does not exceed 3.25 while the specifications on GMCT are that delta TAN cannot exceed 2.0 and the 1-2 shift time must stay between 0.30 and 0.75 seconds throughout the test. For this work, we analyze oil oxidation and changes in oils’ surface tension, drum and band surface degradation and deposit formation. We have found that with respect to the delta TAN limits of the DEXRON ®III-H specification, the GMCT is more severe than the GMOT. The effect of base oil chemistry on oxidation in these tests has been quantified. Oil oxidation is not responsible for the GMCT 1-2 shift time increase. There are two failure modes identified to be responsible for the GMCT 1-2 shift time increase. One is an increase in air dispersed in the oils as they age and the other is thermal degradation of the band friction material. The surface tension of oils decreases as they are aged in the GMCT and the decrease in surface tension is correlated to an increase in 1-2 shift time. As surface tension decreases more air can be dispersed in an oil. As band friction materials are aged the decomposition temperature of the band material (as measured by pressure differential scanning calorimeter (PDSC)) decreases. The drop in PDSC decomposition temperature is associated with the degradation of the band friction material due to oligomerization caused by thermal effects rather than deposit or gl