Patent ID: 6855675

Claim:
A method for lubricating an engine so as to maintain the reduction of friction for a prolonged time under the conditions of use in the engine comprising lubricating said engine with a lubricating oil composition comprising a lubricating base oil and (a) sulfoxymolybdenum dithiocarbamate containing a hydrocarbon group having 8 to 18 carbon atoms, (b) a zinc dialkyldithiophosphate component selected from the group consisting of: (i) zinc dialkyldithiophosphate containing primary alkyl groups having 1 to 18 carbon atoms, (ii) a mixture of zinc dialkyldithiophosphate containing primary alkyl groups having 1 to 18 carbon atoms and zinc dialkyldithiophosphate containing secondary alkyl groups having 3 to 18 carbon atoms, (iii) zinc dialkyldithiophosphate containing primary alkyl groups containing 1 to 18 carbon atoms, and one secondary alkyl group containing 3 to 18 carbons (iv) mixtures thereof, (c) an alkylsalicylate component comprising a mixture of magnesium alkylsalicylate and calcium alkylsalicylate, wherein the magnesium alkylsalicylate does not exceed 50% by weight of said alkylsalicylate component, wherein the amount of molybdenum derived from the sulfoxymolybdenum dithiocarbamate is from 200 to 1000 ppm (weight basis) of the total weight of the composition, the amount of phosphorous derived from the zinc dialkyldithiophosphate component is from 0.04 to 0.15% by weight of the total weight of the composition and the total amount of the alkylsalicylate component is from 0.5 to 10% by weight of the total weight of the composition.