Low viscosity lubricating oil composition

Abstract

The present invention generally relates to lubricating oil compositions useful for reducing NOACK volatility in finished lubricating oils of an internal combustion engine. Also disclosed is a method for reducing NOACK volatility in finished lubricating oils in said engine.

What is claimed is: 
     
         1 . A lubricating oil composition comprising:
 a. a base oil comprising a diester having one of the following structures:   
       
         
           
           
               
               
           
         
       
       wherein each R is independently a C 1 -C 20  saturated or unsaturated alky group, and n is an integer from 1 to 8, wherein the diester has a kinematic viscosity at 100° C. of from 2.5 to 3.5 mm 2 /s according to ASTM D445 and a viscosity index of from 110 to 175 according to ASTM D2270; and
 b. 75-500 ppm of boron based on the entire weight of the lubricating oil composition, wherein the boron is provided by one or more boron-containing dispersants. 
 
     
     
         2 . The lubricating oil composition of  claim 1 , wherein the high shear viscosity at 80° C. of the lubricating composition is less than 4.5 mPa·s. 
     
     
         3 . The lubricating oil composition of  claim 1 , further comprising:
 detergent, anti-wear agent, antioxidant, foam inhibitor, rust inhibitor, dehazing agent, demulsifying agent, metal deactivating agent, friction modifier, pour point depressant, co-solvent, corrosion-inhibitor, ashless dispersant, multifunctional agent, dye, or extreme pressure agent.   
     
     
         4 . The lubricating oil composition of  claim 1 , wherein the boron-containing dispersant is borated polyisobutenyl succinimide or borated polyalkenyl succinic anhydride. 
     
     
         5 . The lubricating oil composition of  claim 1 , further comprising an additional base oil. 
     
     
         6 . A method of reducing evaporation loss in an internal combustion engine comprising lubricating said engine with a lubricating oil composition comprising:
 a. a base oil comprising a diester having one of the following structures:   
       
         
           
           
               
               
           
         
       
       wherein each R is independently selected from the group consisting of C 1 -C 20  saturated or unsaturated alky group and n is an integer from 1 to 8, wherein the diester has a kinematic viscosity at 100° C. of from 2.5 to 3.5 mm 2 /s according to ASTM D445 and a viscosity index of from 110 to 175 according to ASTM D2270; and
 b. 75 to 500 ppm of boron based on the entire weight of the lubricating oil composition, wherein the boron is provided by one or more boron-containing dispersant. 
 
     
     
         7 . The method of  claim 6 , wherein the high shear viscosity at 80° C. of the lubricating composition is less than 4.5 mPa·s. 
     
     
         8 . The method of  claim 6 , wherein the lubricating oil composition further comprises: detergent, anti-wear agent, antioxidant, foam inhibitor, rust inhibitor, dehazing agent, demulsifying agent, metal deactivating agent, friction modifier, pour point depressant, co-solvent, corrosion-inhibitor, ashless dispersant, multifunctional agent, dye, or extreme pressure agent. 
     
     
         9 . The method of  claim 6 , wherein the boron-containing dispersant is borated polyisobutenyl succinimide or borated polyalkenyl succinic anhydride. 
     
     
         10 . The method of  claim 6 , wherein the lubricating oil composition further comprises an additional base oil. 
     
     
         11 . A method of improving fuel efficiency of an engine, wherein the method comprises lubricating the engine with a lubricating oil composition comprising:
 a. a base oil comprising a diester having one of the following structures:   
       
         
           
           
               
               
           
         
       
       wherein each R is independently selected from the group consisting of C 1 -C 20  saturated or unsaturated alky group and n is an integer from 1 to 8, wherein the diester has a kinematic viscosity at 100° C. of from 2.5 to 3.5 mm 2 /s according to ASTM D445 and a viscosity index of from 110 to 175 according to ASTM D2270; and
 b. 75 to 500 ppm of boron based on the entire weight of the lubricating oil composition, wherein the boron is provided by one or more boron-containing dispersant. 
 
     
     
         12 . The method of  claim 11 , wherein the high shear viscosity at 80° C. of the lubricating composition is less than 4.5 mPa·s. 
     
     
         13 . The method of  claim 11 , wherein the lubricating oil composition further comprises: detergent, anti-wear agent, antioxidant, foam inhibitor, rust inhibitor, dehazing agent, demulsifying agent, metal deactivating agent, friction modifier, pour point depressant, co-solvent, corrosion-inhibitor, ashless dispersant, multifunctional agent, dye, or extreme pressure agent. 
     
     
         14 . The method of  claim 11 , wherein the boron-containing dispersant is borated polyisobutenyl succinimide or borated polyalkenyl succinic anhydride. 
     
     
         15 . The method of  claim 11 , wherein the lubricating oil composition further comprises an additional base oil.