JSAE 20030296 SAE 2003-01-1985 Extended-Drain ATF Field Testing in City Transit Buses J. A. Zakarian Chevron Texaco Global Lubricants F. J. Schullo, J. L. Sumiejski, D. R. Vermilya The Lubrizol Corporation 2003 JSAE/SAE International Spring Fuels & Lubricants Meeting Yokohama, Japan May 19-22, 2003 10-2 Gobancho, Chiodaku, Tokyo 102-0076 Japan Tel:+81-3-3262-8211 Fax:+81-3-3261-2204 Downloaded from SAE International by Univ of California Berkeley, Tuesday, July 31, 2018Notice about photocopy In order to photocopy any works from this publication, you or your organization must obtain permission from the following organization which you has been delegated for copyright for clearance by the copyright owner of this publication. Except in the U.S.A. Japan Academic Association for Copyright Clearance (JAACC) 6-41 Akasaka 9-chome, Minato-ku, Tokyo 107-0052 Japan TEL: 81-3-3475-5618 Fax: 81-3-3475-5619 EE-mail:[email protected] In the U.S.A. Copyright Clearance Center, Inc. 222 Rosewood Drive, Danvers, MA 01923 U.S.A. Phone: 1-978-750-8400 Fax:1-978-750-4744 Copyright © 2003 Society of Automotive Engineers of Japan, Inc. Downloaded from SAE International by Univ of California Berkeley, Tuesday, July 31, 2018JSAE 20030296 SAE 2003-01-1985 Extended-Drain ATF Field Testing in City Transit Buses J.A. Zakarian ChevronTexaco Global Lubricants F.J. Schullo, J.L. Sumiejski, and D.R. Vermilya The Lubrizol Corporation Copyright © 2003 Society of Automotive Engineers of Japan, Inc. ABSTRACT City transit buses are a severe environment for an automatic transmission fluid. The fluid must endure very high operating temperatures because of the use of brake retarders, frequent stop-and-go driving, and numerous shifts. There is an increasing trend toward the use of extended-drain, synthetic-based ATFs for such severe service applications. This paper documents a field trial with both synthetic and petroleum-based ATFs at a large municipal bus fleet in Southern California. Three different commercial ATFs, made with either API Group 2, 3, or 4 base oils, respectively, were compared after roughly 80,000 km. and one year of operation. Because of different additive packages in each fluid, not all of the results can be explained by base oil effects alone. However, the base oil is certainly a dominant contributor to the finished fluid performance. The following four variables were monitored by used oil analysis: iron wear, copper wear, viscosity change, and acid number change. The two synthetic-based ATFs showed directionally better performance in copper wear, viscosity change, and acid number increase compared to the Group 2-based ATF. There was no significant difference in ferrous wear protection between the three ATFs. The Group 2-based ATF is capable of providing at least double the OEM- recommended drain interval. The Group 3- and the Group 4-based ATFs can achieve 80,000 km drain intervals, which is four times the interval recommended by the OEM. INTRODUCTION The performance requirements of automatic trans­ missions, and their associated fluids, have risen sharply over the past five years. Customers have come to expect better shift feel and operability, more power, and longer equipment life with no increase in transmission cost. In addition, fleet customers are very concerned about reducing their maintenance and operating costs. OEMs have responded by designing better and more complicated transmissions using highly specialized "fill for life" fluids. However, the demand for longer fluid life comes at the same time that the transmission operating environment has grown much more severe. In particular, operating temperatures have risen sharply because of a number of factors — reduced air flow, noise regulations, emissions targets which result in higher oil coolant temperatures, brake retarders, etc. The requirement for longer fluid life at higher operating temperatures ha