1984-10-01

Low Temperature Pumpability of Engine oils 841388

During the winters of 1980-81 and 1981-82, major pumpability field problems were encountered in the US and Europe even though many of the oils involved met the requirements of the newly adopted SAE J300 SEP80. In an effort to understand these failures, pumpability requirements have been re-examined using a cross section of current production 4-cylinder engines of both the overhead cam and push rod design. Characteristics of these engines were found to be similar to those of the V-8's used in the earlier ASTM program that formed the basis for J300. The same engines all exhibited formal pumping failures using a strongly air-binding oil and a critical temperature cycle. However, the severity of the failures varied widely, perhaps providing clues to the tendency of some of these engines to fail in the field. In an examination of well-behaved (free of wax-gelation tendency) oils, the pumpability of oils based on polymethacrylates was superior to that of oils using either olefin copolymer or hydrogenated styrene-isoprene copolymer VI improvers. None of the laboratory test methods examined was totally reliable in predicting engine performance.

SAE MOBILUS

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