Abstract: A method for deconditioning an engine used in evaluating the fuel economy derived from lubricating oils wherein a deconditioning oil is added to the engine after removal of the test lubricating oil, the deconditioning oil comprising a lubricating oil composition containing a selected overbased metal salt or a selected neutral metal salt, the salt being selected from the group consisting of alkali metal or alkaline earth metal sulfonates, phenates, phosphonates and thiophosphonates.

Abstract: Carboxamide compositions comprising N-substituted amides of polyisobutylcarboxylic acids, said acids consisting essentially of a mixture of(i) at least about 80%, by weight, of a polyisobutylcarboxylic acid component characterized by substantially all carboxyl groups being attached to tertiary carbon atoms, and by less than about 20% of said acid component being extractable by successive treatments at 25.degree. C with aqueous alkali and with water, and(ii) up to about 20%, by weight, of a neutral polyisobutyl component, the polyisobutyl portions of components (i) and (ii) having an average molecular weight of about 750 to 3000;The N-substituted component of the carboxamide having the formula, --N(R)Z, where R is hydrogen or lower alkyl and Z is a particular heterocyclic or aliphatic polyamine.