Long life lubricating oil with enhanced oxidation and nitration resistance

A lubricating oil composition comprising:

• a major amount of an oil of lubricating viscosity;
• a mixture of neutral and overbased metallic detergents selected from the group consisting essentially of alkaline earth metal sulfonates, phenates, alkylsalicylates and mixtures thereof in an amount sufficient to provide the composition with a sulfated ash content of from about 0.2 wt % to about 2.0 wt %;
• a trinuclear molybdenum compound having the formula
• Mo3SkLnQz
• where L is an independently selected ligand, n is from 1 to 4, k is from 4 to 7, Q is a neutral electron donating moiety, and z is from 0 to 5;
• from 0 to 2.0 vol % of a dihydrocarbyl thiocarbamoyl compound having the formula;
• 3
• where R1, R2, R3 and R4 are the same or different alkyl groups of from 3 to 30 carbon atoms;
• X is S, S—S, S[Parenopenst]CH2[Parenclosest]yS, S—CH2CH2(CH3)—S;
• and y is an integer of 1 to 3;
• the amount of trinuclear molybdenum compound and dihydrocarbyl thiocarbomyl compound being in the range of about 0.1 vol % to about 2.0 vol %.

A method for enhancing the life of a lubricating oil as evidenced by a reduction in viscosity increase, oxidation and nitration, the method comprising:

• adding to the lubricating oil additives comprising:
• a mixture of neutral and overbased metallic detergents selected from the group consisting essentially of alkaline earth metal sulfonates, phenates, alkylsalicylates, and mixtures thereof in an amount sufficient to provide the composition with a sulfated ash content of from about 0.2 wt % to about 2.0 wt %;
• at least 0.1 vol % of a trinuclear molybdenum compound having the formula
• Mo3SkLnQz
• Where L is an independently selected ligand, n is 1 to 4, k is 4 to 7, Q is a neutral electron donating moiety, and z is 0 to 5;
• a dihydrocarbylthiocarbomyl compound;
• the amount of trinuclear molybdenum compound and dihydrothiocarbomyl compound being in the range of 0.1 vol % about 2.0 vol %.