| abstract |
PURPOSE:To improve the load bearing quality, abrasion resistance, thermal and oxidation stability of a lubricating oil to thereby prevent the oil from causing sludge formation, coloration or discoloration by mixing a base oil with zinc dithiophosphate and a 16-24C unsaturated aliphatic alcohol at a specific mixing ratio. CONSTITUTION:A base oil (A) having a viscosity of 50,000-10,000cst at 40 deg.C (e.g. a hindered ester oil) is mixed with 0.05-5wt.% zinc dithiophosphate (B) represented by the formula (wherein R<1> to R<4> each represent a primary or secondary alkyl, cycloalkyl, aryl or alkylaryl); 0.01-10wt.% 16-24C unsaturated aliphatic alcohol (C) having an iodine value of 50 or more (e.g. cis-11- hexadecen-1-ol); and optionally 0.01-50wt.% at least one compound (D) selected from a phosphoric or phosphorous acid ester (e.g. triphenyl phosphate), an amine salt of a phosphoric or phosphorous acid ester and a detergent-dispersant (e.g. a petroleum-based sulfonate). These components are mixed in such a way that the weight ratio of the component C to the component B will be 0.1 to 10. |