Marine diesel engine lubricating oil compositions

A method of thickening a lubricating oil composition in a marine diesel internal combustion engine, the method comprising adding to said engine a lubricating oil composition comprising:

• (a) at least 40 wt. % of an oil of lubricating viscosity having a kinematic viscosity at 100° C. of from 4.0 to less than 8.5 mm2/s;
• and
• (b) one or more olefin copolymers having a number average molecular weight of 30,000 to 120,000;
• and
• wherein the marine diesel lubricating oil composition has a TBN of greater than 30 mg KOH/g, and further wherein the marine diesel lubricating oil composition is a monograde lubricating oil composition meeting the specifications for SAE J300 revised January 2015 requirements for a SAE 30, SAE 40, SAE 50 or SAE 60 monograde lubricating oil.

A method of controlling deposit formation in an internal combustion engine, the method comprising operating the internal combustion engine with a lubricating oil composition comprising:

• (a) at least 40 wt. % of an oil of lubricating viscosity having a kinematic viscosity at 100° C. of from 4.0 to less than 8.5 mm2/s;
• and
• (b) one or more olefin copolymers having a number average molecular weight of 30,000 to 120,000;
• and
• wherein the marine diesel lubricating oil composition has a TBN of greater than 30 mg KOH/g, and further wherein the marine diesel lubricating oil composition is a monograde lubricating oil composition meeting the specifications for SAE J300 revised January 2015 requirements for a SAE 30, SAE 40, SAE 50 or SAE 60 monograde lubricating oil.

A marine diesel engine lubricating oil composition comprising:

• (a) at least 40 wt. % of an oil of lubricating viscosity having a kinematic viscosity at 100° C. of from 4.0 to less than 8.5 mm2/s;
• and
• (b) one or more olefin copolymers having a number average molecular weight of 30,000 to 120,000, wherein the one or more olefin copolymers are present, on an actives basis, at 1.0 wt. % or greater of the lubricating oil composition;
• and
• wherein the marine diesel engine lubricating oil composition is a monograde lubricating oil composition meeting the specifications for SAE J300 revised January 2015 requirements for a SAE 30, SAE 40, SAE 50 or SAE 60 monograde lubricating oil.