Synthetic lubricant composition of improved oxidation stability

1,129,964. Lubricants. BRITISH PETROLEUM CO. Ltd. 22 Dec., 1965 [15 Jan., 1965], No. 1868/65. Heading C5F. A lubricant comprises (i) a liquid, neutral ester base oil having at least two ester linkages per molecule prepared from (a) a mono- and/or polyhydric C 5 -C 15 alcohol having no #-hydrogen atoms with respect to any -OH group and (b) a C 2 -C 14 mono- and/or polycarboxylic acid and (ii) 1-15 p.p.m. of one or more compounds which are organic metal complexes or salts which oxidize or reduce the organic radicals formed during oxidative degradation of esters. C 8+ Acid salts and complexes of the transition metals, cerium and copper are preferred as component (ii), e.g. manganous and cobaltous acetylacetonates, cupric phthalocyanine and cupric stearate. Specified esters are trimethylolpropane tricaprylate and the reaction product of caprylic acid, trimethylol propane and sebacic acid. The composition may also contain metal deactivators, e.g. benzotriazole, amine-antioxidants, e.g. p, p1-dioctyldiphenylamine, and other conventional additives.