Method for lubricating a continuously variable transmission

摘要

Continuously variable transmissions are lubricated by supplying to the transmission a composition of an oil of lubricating viscosity and an oil-soluble zinc salt containing at least one hydrocarbyl group of at least 4 carbon atoms. The amount of the zinc salt is sufficient to provide an increased steel-on-steel dynamic coefficient of friction for the composition, being at least 0.125. The composition is substantially free from thiophosphate salts and exhibits a copper corrosion rating of 1B or better (ASTM-130).