Patent ID: 8618029

Claim:
A lubricating oil additive comprising a product obtained by the process of: (I) preparing a surfactant system comprising: (A) at least one alkyl aromatic sulfonate of an alkaline-earth metal comprising: (i) from about 50 wt % to 100 wt % of a linear mono alkyl aromatic sulfonate in which the linear mono alkyl group contains from about 14 to 40 carbon atoms, and the mole % of the aromatic sulfonate group fixed on the 1 or 2 position of the linear alkyl chain is from about 10% to 70%; and (ii) from about 0 wt % to 50 wt % of a branched mono alkyl aromatic sulfonate in which the branched alkyl group contains from about 14 to 30 carbon atoms; and (B) at least one oil-soluble reactant selected from the group consisting of: (i) an alkylhydroxybenzoic acid or the alkaline metal or alkaline-earth metal salt thereof; (ii) a carboxylate detergent-dispersant obtained by: (a) neutralizing alkylphenols using an alkaline-earth metal base forming an intermediate product; and (b) carboxylating the intermediate product using carbon dioxide so that at least 5 wt % of the original alkylphenol starting material has been converted to alkaline-earth metal single aromatic-ring hydrocarbyl salicylate; and (iii) a sulfurized or non-sulfurized alkylphenol or the alkaline metal or alkaline-earth metal salt thereof, wherein the alkyl group in each of (B)(i) to (B)(iii) is independently a linear or branched alkyl group, or mixture of linear and branched alkyl groups having from about 9 to 160 carbon atoms; and (II) reacting the resultant surfactant system with a source of alkaline-earth metal and at least one acidic co-agent; wherein the proportion of salified alkylphenol surfactant in the surfactant system is less than 15 wt %.