Methods and compositions for reducing wear in heavy-duty diesel engines

1. A heavy-duty diesel engine lubricating oil composition comprising a major amount of an oil of lubricating viscosity,

a) a sufficient amount of an overbased detergent additive to control deposits during operation of a heavy-duty diesel engine;

b) a sufficient amount of a neutral alkali or alkaline earth metal sulfonate having a TBN of less than 25 to control deposits during high temperature operation of said heavy-duty diesel engine; and

c) a sufficient amount of a dispersed, hydrated alkali metal borate to inhibit wear during operation of said heavy-duty diesel engine.

2. The lubricating oil composition according to claim 1 , wherein sufficient amounts of the overbased detergent additive are employed to provide a TBN to the finished lubricant composition of at least about 5.

3. The lubricating oil composition according to claim 2 , wherein the finished lubricant composition has a TBN of from about 5 to 20.

4. The lubricating oil composition according to claim 3 , wherein the finished lubricant composition has a TBN of from 12 to 15.

5. The lubricating oil composition according to claim 1 , wherein the dispersed hydrated alkali metal borate composition is present in an amount of from about 0.1 to about 5 weight percent of the total weight of the lubricant composition.

6. The lubricating oil composition according to claim 5 , wherein the dispersed hydrated alkali metal borate composition is present in an amount of from about 0.2 to 2 weight percent.

7. The lubricating oil composition according to claim 1 , wherein the dispersed hydrated alkali metal borate is a dispersed hydrated potassium borate.

8. The lubricating oil composition according to claim 1 , wherein the neutral alkali or alkaline earth metal sulfonate is present in an amount of from about 0.2 to 5 weight percent based on the total weight of the composition.

9. The lubricating oil composition according to claim 1 , which further comprises an anti-wear and anti-oxidant effective amount of a molybdenum/nitrogen-containing complex.

10. A method for controlling wear and deposits during operation of a heavy-duty diesel engine, comprising operating the heavy duty diesel engine with a lubricating oil composition, wherein said lubricating oil composition comprises:

a) a major amount of an oil of lubricating viscosity,

b) a sufficient amount of an overbased detergent additive to control deposits during operation of said heavy-duty diesel engine;

c) a sufficient amount of a neutral alkali or alkaline earth metal sulfonate having a TBN of less than 25 to control deposits during high temperature operation of said heavy-duty diesel engine; and

d) a sufficient amount of a dispersed, hydrated alkali metal borate to inhibit wear during operation of said heavy-duty diesel engine.