Use of polymeric shear agents to minimize variations in viscosity in medium -speed diesel engine lubricating oils

摘要

Zinc-free medium-speed diesel engine lubricating oils containing a polymeric shear agent to minimize the variation in viscosity due to oxidation and soot thickening. The medium-speed diesel engine lubricating oil composition comprises: (a) a major amount of a zinc-free baseline oil; and (b) a minor amount of a polymeric shear agent, which gives from 1.0 to 2.7 cSt at 100 DEG C incremental increase in viscosity over that baseline oil; and wherein the medium-speed diesel engine lubricating oil composition meets the SAE 40 specification. The polymeric shear agents which may be used are those which can be dissolved in a mineral oil, such as ungrafted and grafted carbon-carbon polymers or copolymers.