Cam and Lifter Wear as Affected By Engine Oil Zdp Concentration and Type

Document Number: 770087

Date Published: February 1977

Author(s):
Loren G. Pless - Fuels and Lubricants Dept., Research Labs, General Motors Co
John J. Rodgers - Fuels and Lubricants Dept., Research Labs, General Motors Co

Abstract:
The recent increase in excessive camshaft and lifter wear after extended service has shown that some SE-quality engine oils do not provide adequate protection.

To determine the effects of oil additives on wear, controlled tests were run using 1972-1974 model cars, unleaded gasoline, and either SE commercial products or experimental formulations. Field experience with 1970-1975 model trucks, leaded gasoline, and SE/CC or SE/CD oils was also investigated.

With some commercial oils, in both controlled tests and field experience, excessive wear sometimes occurred after extended service, even with recommended oil-change intervals. Generally, protection from excessive wear was best provided by those oils containing predominantly alkyl ZDP (zinc dithiophosphate) antiwear additive instead of aryl ZDP. These results show that a laboratory engine test is needed to evaluate the long-term wear protection of engine oils.

Product Status: In Stock

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