Synergistic combinations of hydrated potassium borate, antiwear agents, and organic sulfide antioxidants

摘要

A synergistic extreme-pressure lubricating composition comprising an oil of lubricating viscosity having dispersed therein: (1) 1-60 weight percent of hydrated potassium borate microparticles having a boron to potassium ratio of about 2.5 to 4.5 (2) from 0.01 to 5.0 weight percent of an antiwear agent selected from (a) a zinc dihydrocarbyl dithiophosphate having from 4 to 20 carbons in each hydrocarbyl group; (b) a C1-C20 amine salt of a dihydrocarbyl dithiophosphoric acid having from 4 to 20 carbons in each hydrocarbyl group; (c) a zinc alkyl aryl sulfonate; or (d) mixtures thereof, and (3) from 0.1 to 5 weight percent of an oil-soluble antioxidant organic sulfur compound containing from 3 to 40 weight percent sulfur, which sulfur is present as organic sulfide or polysulfide or mixtures thereof.