Lubricating oil with improved wear properties

Abstract

Provided is a lubricating oil composition for internal combustion engines comprising at least one hydrocarbon base stock which is determined to exhibit a 40° C. PVC/100° C. PVC ratio approaching one or greater, and one or more lubricating additives. Also provided is a method for preparing such a composition, which includes determining the 40° C. PVC/100° C. PVC ratio of a hydrocarbon base stock oil, and selecting a hydrocarbon base stock oil which exhibits a 40° C. PVC/100° C. PVC ratio approaching one. One or more lubricating additives is then added to the selected base stock oil.

1 . A lubricating oil composition for internal combustion engines comprising:
 a) at least one hydrocarbon base stock which is selected once it is determined to exhibit a 40° C. PVC/100° C. PVC ratio approaching one or greater; and   b) one or more lubricating additives.   
     
     
         2 . The composition of  claim 1 , wherein the at least one hydrocarbon base stock is blended with a minor amount of a different base stock. 
     
     
         3 . The composition of  claim 2 , wherein the different base stock is a Fischer-Tropsch derived base oil. 
     
     
         4 . The composition of  claim 1 , wherein the at least one hydrocarbon base stock which is selected because it exhibits a 40° C. PVC/100° C. PVC ratio is a Fischer-Tropsch derived base oil. 
     
     
         5 . The composition of  claim 1 , wherein the ratio is at least 0.85. 
     
     
         6 . The composition of  claim 1 , wherein the ratio is at least 0.90. 
     
     
         7 . The composition of  claim 1 , wherein the ratio is at least 0.95. 
     
     
         8 . The composition of  claim 3 , wherein the Fischer-Tropsch derived base oil blended with the hydrocarbon base stock exhibits a kinematic viscosity at 100° C. of at least 7 mm 2 /sec. 
     
     
         9 . The composition of  claim 3 , wherein the Fischer-Tropsch derived base oil blended with the hydrocarbon base stock exhibits a kinematic viscosity at 100° C. of at least 10 mm2/sec. 
     
     
         10 . The composition of  claim 1 , wherein the at least one hydrocarbon base stock exhibits a kinematic viscosity at 100° C. in the range of from 3 to 12 mm 2 /sec. 
     
     
         11 . The composition of  claim 1 , wherein the at least one hydrocarbon base stock exhibits a kinematic viscosity at 100° C. in the range of from 4 to 10 mm 2 /sec. 
     
     
         12 . The composition of  claim 1 , wherein the composition contains no viscosity modifier. 
     
     
         13 . The composition of  claim 1 , wherein the composition contains one or more detergents. 
     
     
         14 . The composition of  claim 1 , wherein the composition contains one or more dispersants. 
     
     
         15 . The composition of  claim 1 , wherein the composition contains one or more anti-oxidants. 
     
     
         16 . The lubricating oil composition of  claim 1 , wherein the composition further comprises one or more conventional base oils, and wherein the conventional base oil is a maximum of 30 weight percent based on the total weight of the lubricating oil composition. 
     
     
         17 . A method for lubricating an internal combustion engine and reducing the wear comprising lubricating the internal combustion engine with the lubricating oil composition of  claim 1 . 
     
     
         18 . A method for lubricating an internal combustion engine and reducing the wear comprising lubricating the internal combustion engine with the lubricating oil composition of  claim 3 . 
     
     
         19 . A method for preparing the lubricating oil composition of  claim 1 , comprising:
 a) determining the 40° C. PVC/100° C. PVC ratio of a hydrocarbon base stock oil;   b) selecting a hydrocarbon base stock oil once it is determined to have a 40° C. PVC/100° C. PVC ratio approaching one; and   c) adding one or more lubricating additives.   
     
     
         20 . The method of  claim 19 , further comprising blending the hydrocarbon base stock oil of b) with a Fischer-Tropsch derived base oil. 
     
     
         21 . The method of  claim 19 , wherein the hydrocarbon base stock oil is a Fischer-Tropsch derived base oil. 
     
     
         22 . The method of  claim 19 , wherein the hydrocarbon base stock oil has a ratio of at least 0.85. 
     
     
         23 . The method of  claim 19 , wherein the hydrocarbon base stock oil has a ratio of at least 0.90. 
     
     
         24 . The method of  claim 19 , wherein the hydrocarbon base stock oil has a ratio of at least 0.95.