Abstract: A method of making a methyl methacrylate-lauryl methacrylate copolymer for use as a non-dispersant, shear stabilizing, wear inhibiting and VI-improving additive in hydraulic fluids and lubricating oils comprises:(a) first reacting a weight ratio of 10-20 parts methyl methacrylate to 80-90 parts lauryl methacrylate in the presence of 1.0-2.0 weight percent of an alkyl mercaptan at a temperature of 150.degree.-200.degree. F.;(b) further reacting the reaction product of step (a) in the presence of 0.01-1.0 weight percent of azobis (isobutyronitrile) catalyst at a temperature of 150.degree.-200.degree. F.; and(c) thereafter heating the reaction product of step (b) at a temperature of 200.degree.-300.degree. F.A concentrate composition comprising a base oil and an effective amount of the methyl methacrylate-lauryl methacrylate copolymer is particularly useful as an additive for use in high-VI hydraulic fluids and lubricating oils.

Abstract: Lubricating oils with superior oxidation inhibition result from the combination of additives in a lubricating oil base; the ashless additive combination comprising methylene bis(dibutyl dithiocarbamate) and 4-methyl-2,6-ditertiary butyl phenol. The above combination of additives displays synergistic activity as an oxidation inhibitor.