Lubricant additives and lubricant compositions having improved frictional characteristics

1. A lubricating oil composition, comprising a base oil and

a) a dihydrocarbyl dithiophosphate metal salt antiwear compound in an amount sufficient to provide from about 100 to about 1000 ppm by weight phosphorus based on a total weight of the lubricant composition, and

b) from about 0.1 to about 2% by weight based on a total weight of the lubricating oil composition of an unsaturated heat bodied vegetable oil, different from the base oil, wherein the base oil is present in an amount from about 50 wt. % to about 99 wt. % based on the total weight of the lubricating oil composition.

2. The lubricating oil composition of claim 1 , wherein the heat bodied vegetable oil is present in an amount from about 0.2 to about 1.0 wt. % based on a total weight of the lubricant composition.

3. The lubricating oil composition of claim 1 , wherein the dihydrocarbyl dithiophosphate metal salt antiwear compound is present in an amount sufficient to provide from about 200 to about 800 ppm by weight phosphorus based on a total weight of the lubricant composition.

4. The lubricating oil composition of claim 1 , wherein the dihydrocarbyl dithiophosphate metal salt antiwear compound comprises a mixture of (A) a metal-containing phosphorus antiwear compound derived from primary alcohols and (B) a metal-containing phosphorus antiwear compound derived from secondary alcohols, wherein a weight ratio of (A) to (B) based on ppm by weight phosphorus provided by (A) and (B) to the lubricant composition ranges from 0:1 to about 4:1.

5. The lubricating oil composition of claim 1 , wherein the dihydrocarbyl dithiophosphate metal salt antiwear compound is derived from a mixture of primary and secondary alcohols.

6. The lubricating oil composition of claim 1 , wherein the heat bodied vegetable oil has a number average molecular weight ranging from about 400 to about 5,000 Daltons and a polydispersity (M n /M w ) ranging from about 1.2 to about 3.5.

7. The lubricating oil composition of claim 1 , wherein the lubricating oil composition is an engine oil.

8. A method for reducing a boundary friction coefficient of a lubricating oil composition, comprising lubricating an engine with the lubricating oil composition comprising a base oil and

a) a dihydrocarbyl dithiophosphate metal salt antiwear compound in an amount sufficient to provide from about 100 to about 1000 ppm by weight phosphorus based on a total weight of the lubricant composition, and

b) from about 0.1 to about 2% by weight based on a total weight of the lubricating oil composition of an unsaturated heat bodied vegetable oil, different from the base oil, wherein the base oil is present in an amount from about 50 wt. % to about 99 wt. % based on the total weight of the lubricating oil composition.

9. The method of claim 8 , wherein the heat bodied vegetable oil is present in an amount from about 0.2 to about 1.0 wt. % based on a total weight of the lubricant composition.

10. The method of claim 8 , wherein the dihydrocarbyl dithiophosphate metal salt antiwear compound is present in an amount sufficient to provide from about 200 to about 800 ppm by weight phosphorus based on a total weight of the lubricant composition.

11. The method of claim 8 , wherein the dihydrocarbyl dithiophosphate metal salt antiwear compound comprises a mixture of (A) a metal-containing phosphorus antiwear compound derived from primary alcohols and (B) a metal-containing phosphorus antiwear compound derived from secondary alcohols, wherein a weight ratio of (A) to (B) based on ppm by weight phosphorus provided by (A) and (B) to the lubricant composition ranges from 0:1 to about 4:1.

12. The method of claim 8 , wherein the dihydrocarbyl dithiophosphate metal salt antiwear compound is derived from a mixture of primary and secondary alcohols.

13. The method of claim 8 , wherein the heat bodied vegetable oil has a number average molecular weight ranging from about 400 to about 5,000 Daltons and a polydispersity (M n /M w ) ranging from about 1.2 to about 3.5.

14. A method for improving the fuel economy of a vehicle comprising lubricating the engine of the vehicle with a lubricating oil composition comprising a base oil and

a) a metal-containing phosphorus antiwear compound in an amount sufficient to provide from about 100 to about 1000 ppm by weight phosphorus based on a total weight of the lubricant composition, and

b) from about 0.1 to about 2% by weight based on a total weight of the lubricating oil composition of an unsaturated heat bodied vegetable oil, different from the base oil wherein the base oil is present in an amount from about 50 wt. % to about 99 wt. % based on the total weight of the lubricating oil composition.

15. The method of claim 14 , wherein the lubricant composition comprises from about 0.2 to about 1.0 wt. % of component (b) based on a total weight of the lubricant composition.

16. The method of claim 14 , wherein the amount of component (a) is sufficient to provide the lubricant composition with from about 200 to about 800 ppm by weight phosphorus based on a total weight of the lubricant composition.

17. The method of claim 14 , wherein component (a) is derived from a mixture of primary and secondary alcohols.

18. The method of claim 14 , wherein component (b) has a number average molecular weight ranging from about 500 to about 5,000 Daltons and a polydispersity (Mn/Mw) ranging from about 1.2 to about 3.5.