Lubricating oil composition

A method for lubricating an engine so as to maintain the reduction of friction for a prolonged time under 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 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 a 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.
• (d) succinimide containing boron
• 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.
• the amount of boron derived from the succinimide containing boron is from 0.005 to 0.06% by weight of the total weight of the composition, and the boron/nitrogen ratio regarding the number of atoms contained in the succinimide contained boron is from 0.05 to 1.5.