Amoco Corporation

Ethyl Petroleum Additives, Inc.

David A Hutchison

Lionel D Moore

Richard D Stauffer

There is provided a lubricating oil composition for use in medium speed diesel engines, such as railroad locomotive diesel engines. This lubricating oil composition comprises an oil of lubricating viscosity and a minor amount of a reaction product that is obtained by reacting an alkyl-substituted dicarboxylic acid compound selected from the group consisting of alkyl-substituted dicarboxyic acids, alkyl-substituted dicarboxylic acid anhydrides, and mixtures thereof with a basic salt of aminoguanidine under selected conditions that will provide a product rich in alkyl bis-3-amino-1,2,4-triazole.

Medium speed diesel engine lubricating oils

A lubricating composition, preferably essentially free of zinc dihydrocarbyldithiophosphate compounds, and optionally free of chlorine containing silver lubricity agents, comprising a major proportion of an oil of lubricating viscosity and a minor amount of a silver protective agent comprising the reaction product of a C.sub.5 to C.sub.60 carboxylic acid and at least one amine selected from the group consisting of (1) guanidine, urea, and thioruea compounds; (2) C.sub.1 to C.sub.20 hydrocarbyl or hydroxy-substituted hydrocarbyl mono-amines, alkylene diamines, and (3) polyalkylene polyamines; and N-alkyl glycine.

Chlorine-free silver protective lubricant composition (I)

Silver protection in lubricant compositions is afforded by the combination of organo-sulfur compounds and hydrocarbon-substituted 1,2,4-triazoles, the latter being obtained by reaction of a substantially aliphatic, substantially saturated hydrocarbon-substituted dicarboxylic acid with an aminoguanidine compound. The invention is also directed to a method of silver protection utilizing the above combination.

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Naperville, IL, United States of America

David A Hutchison