| abstract |
A lubricating oil composition is described which comprises a major amount of an oil of lubricating viscosity and (A) at least about 1% by weight of at least one carboxylic derivative composition produced by reacting (A-1) at least one substituted succinic acylating agent containing at least about 50 carbon atoms in the substituent with (A-2) from about 0.5 equivalent up to about 2 moles, per equivalent of acylating agent (A-1), of at least one amine compound characterized by the presence within its structure of at least one HN<group; and (B) an amount of at least one alkali metal overbased salt of a carboxylic acid or a mixture of a carboxylic acid and an organic sulfonic acid sufficient to provide at least about 0.002 equivalent of alkali metal per 100 grams of the lubricating oil composition provided that when the alkali metal salt comprises a mixture of overbased alkali metal salts of a hydrocarbyl-substituted carboxylic acid and a hydrocarbyl-substituted sulfonic acid, then the carboxylic acid comprises more than 50% of the acid equivalents of the mixture; and either (C-1) at least one magnesium overbased salt of an acidic organic compound provided that the lubricating composition is free of calcium overbased salts of acidic organic compounds; or (C-2) at least one calcium overbased salt of an acidic organic compound provided that the lubricating composition is free of magnesium overbased salts of acidic organic compounds. |