High temperature synthetic lubricants and related engine lubricating systems

A method of lubricating an internal combustion engine operating at a ring reversal temperature of at least 343.degree. C. which comprises contacting the moving parts of the engine with a lubricant composition comprising a predominant amount of a non-neo-carbon polycarboxylic ester ingredient capable of escaping with the exhaust gases of the engine when operated at such a temperature and a lesser amount of an organophosphorus compound, wherein said polycarboxylic ester ingredient comprises a blend of a predominant amount of a benzene tricarboxylic ester with a lesser amount of a benzene dicarboxylic acid ester.