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 SERIES 2004-01-3028 Estimating the Useful Life of an ATF Using an Integrated Bulk Oxidation and Friction Degradation Model Brent D. Calcut and Reuben Sarkar General Motors Powertrain James L. Linden General Motors Research Reprinted From: Oils , Rheology, Tribology, and Driveline Fluids (SP-1894) Powertrain & Fluid Systems Conference & Exhibition Tampa, Florida USA October 25-28, 2004Downloaded from SAE International by American Univ of Beirut, Saturday, July 28, 2018All 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: permissions@sae.orgFax: 724-772-4891Tel: 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 Service@sae.org ISSN 0148-7191Copyright © 2004 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 American Univ of Beirut, Saturday, July 28, 2018 12004-01-3028 Estimating the Useful Life of an ATF Using an Integrated Bulk Oxidation and Friction Degradation Model Brent D. Calcut and Reuben Sarkar General Motors Powertrain James L. Linden General Motors Research Copyright © 2004 SAE International ABSTRACT An integrated approach to modeling end of useful life of an automatic transmission fluid (ATF) has been developed. The flexible fluid life model allows either predictive or real-time calculations of the end of useful fluid life under different transmission design strategies and customer driver behaviors as reflected in operating temperatures, shift characteristics, fluid volume and fluid distribution throughout the transmission. An estimation of remaining useful fluid life is monitored using two metrics, namely bulk oxidation, as a general indi cator of fluid quality, and frictional degradation, as an indicator of shift quality. As operating conditions increase in severity, ATF is subjected to conditions that may shorten its life. Using the developed technique, ATF useful life can be better predicted. INTRODUCTION Methods for estimating the end of useful life of automatics transmission flui ds offer benefits to the customer, OEM, supplier and the environment. The customer benefits through accu rate notification of the proper mileage to change their fluid based upon their driving habits. Customers driving under severe conditions will change their fluid in a suitable time frame to protect the transmission. Those under light duty service may be able to exceed conventional 100,000 mile change interval thereby saving them time and money. OEMs will benefit, in particular with respect to severe service fleet operations, from potentially lower warranty co sts by ensuring the fluid is changed at the proper time. The environment will benefit by informed customers who only change their fluid when it is actually needed. For example, a customer driving with infrequent trailer towing or through hilly terrains may be categorized as severe service driver, according to the current owner’s manual, while practically having transmission fluid tha