Lubricating oil additive system particularly useful for natural gas fueled engines

A natural gas engine lubricating oil comprising:

• about 1 wt. % to about 8 wt. % of one or more dispersants;
• about 1 wt. % to about 8.5 wt. % of one or more detergents;
• about 0.2 wt. % to about 1.5 wt. % of one or more wear inhibitors;
• about 0.6 wt. % to about 2.5 wt. % liquid 3,5-di-t-butyl 4-hydroxy phenol propionate, C7-C9 alkyl ester;
• and
• about 6 wt. % to about 97 wt. % of at least one of Group II and Group III base oil;
• wherein,
• said lubricating oil has a total ash content of about 0.1 wt. % to 1.5 wt. % as determined by ASTM D874.

A natural gas engine lubricating oil comprising:

• about 1 wt. % to about 8 wt. % of one or more dispersants;
• about 1 wt. % to about 8.5 wt. % of one or more detergents;
• about 0.2 wt. % to about 1.5 wt. % of one or more wear inhibitors;
• about 0.6 wt. % to about 2.5 wt. % liquid 3,5-di-t-butyl 4-hydroxy phenol propionate, C7-C9 alkyl ester as an anti-oxidant;
• and
• about 6 wt. % to about 97 wt. % of at least one of Group II and Group III base oil;
• wherein,
• said lubricating oil has a total ash content of about 0.1 wt. % to 1.5 wt. % as determined by ASTM D874, and
• said lubricating oil contains no other antioxidant additive.

A natural gas engine lubricating oil comprising:

• about 0.6 wt. % to about 2.5 wt. % of one or more liquid hindered phenols of the general formula:
• wherein R is a C7 to C9 alkyl group;
• a molybdenum oxidation inhibitor;
• and a major amount of at least one of Group II and Group III base oils;
• wherein:
• said lubricating oil has a total ash content of about 0.1 wt. % to 1.5 wt. % as determined by ASTM D874;
• and
• the concentration of the molybdenum oxidation inhibitor is no more than 0.5 wt. %.

A natural gas engine lubricating oil comprising:

• about 0.2 wt. % to about 3.0 wt. % of one or more liquid hindered phenols of the general formula:
• wherein R is a C7 to C9 alkyl group;
• and a major amount of at least one of Group II and Group III base oils;
• wherein:
• said lubricating oil has a total ash content of about 0.1 wt. % to 1.5 wt. % as determined by ASTM D874;
• and
• said lubricating oil contains no molybdenum oxidation inhibitor.