Exxonmobil Research and Engineering Company

Jeffrey Robert Torkelson

Jason Zhisheng Gao

Brandon T Weldon

Christopher J May

Riccardo Conti

Steven Kennedy

Paul Simon Woolley

Periodically heating a soot containing engine lubricant to a temperature in the range of about 115&#xb0; C. to about 150&#xb0; C. is effective in controlling soot induced viscosity increase of the lubricant. The period at which heating is conducted may be a function of the number of hours the engine has been operated or it may be based on the oil condition.

Method for controlling soot induced lubricant viscosity increase

This invention relates to a lubricating oil composition comprising a base stock and an antioxidant comprising an oil soluble trinuclear organomolybdenum compound of the generic formula: Mo S &mdash;(Q) (1) wherein x is from 4 to 10 and Q is a core group, which may be a ligand, and at least one other compound selected from a phenolic and an aminic compound wherein the basestock has a kinematic viscosity at 100&deg; C. (KV ) from about 2 cSt to 20 cSt (2&times;10 to 20&times;10 m /sec) and a saturates content of at least 85%. The composition has a high oxidation stability, reduced deposit formation and is capable of giving rise to good fuel economy improvement.

Lubricating oil compositions

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Woolwich, NJ, United States of America

Jeffrey Robert Torkelson