Lubricating oil composition providing wear protection at low viscosity

Abstract

Provided is a lubricating oil comprising: (a) a major amount of an oil of lubricating viscosity, (b) a dispersant polymethacrylate (DPMA) VII, (c) a non-dispersant ethylene-based olefin copolymer viscosity index improver, (d) a magnesium containing detergent; wherein the lubricating oil composition is substantially free of molybdenum containing element. Also provided is a method for improving friction and reducing wear in an internal combustion engine using said engine lubricating oil composition.

What is claimed is: 
     
         1 . A lubricating oil composition having a HTHS viscosity at 150° C. in a range of about 1.3 to about 2.9 cP, comprising:
 a) a major amount of an oil of lubricating viscosity having a kinematic viscosity at 100° C. in a range of 1.5 to 6.0 mm 2 /s; 
 b) a dispersant polymethacrylate (DPMA) VII having a Mw of from 200,000 g/mol to 450,000 g/mol; 
 c) a non-dispersant ethylene-based olefin copolymer viscosity index improver having a Mw of from 50,000 g/mol to 150,000 g/mol and a total ethylene content of about 30 wt % to about 70 wt %; 
 d) from about 200 to about 1000 ppm of magnesium from a magnesium containing detergent; and
 wherein the lubricating oil composition is substantially free of molybdenum containing element. 
 
 
     
     
         2 . The lubricating oil composition of  claim 1 , further comprising from 1 to 10 wt. %. of an ester base oil. 
     
     
         3 . The lubricating oil composition of  claim 1 , wherein the magnesium containing detergent is a magnesium salicylate derived from a C 20 -C 24  isomerized normal alpha olefin. 
     
     
         4 . The lubricating oil composition of  claim 1 , wherein the non-dispersant ethylene-based olefin copolymer viscosity index improver has a total ethylene content of about 55 to 65 wt. %. 
     
     
         5 . The lubricating oil composition of  claim 1 , wherein the non-dispersant ethylene-based olefin copolymer viscosity index improver has a Mw of from 70,000 g/mol to 110,000 g/mol. 
     
     
         6 . The lubricating oil composition of  claim 1 , wherein the a dispersant polymethacrylate (DPMA) VII have a Mw of from 200,000 g/mol to 300,000 g/mol. 
     
     
         7 . The lubricating oil composition of  claim 1 , wherein the dispersant polymethacrylate VII comprise monomer units of:
 (a) 0 to 40% by weight of one or more ethylenically unsaturated ester compounds of the formula (I):   
       
         
           
           
               
               
           
         
         wherein R is hydrogen or methyl, R 1  is a saturated or unsaturated linear or branched alkyl radical having 1 to 5 carbon atoms or a saturated or unsaturated cycloalkyl group having 3 to 5 carbon atoms, R 2  and R 3  are each independently hydrogen or a group of the formula —COOR′ wherein R′ is hydrogen or a saturated or unsaturated linear or branched alkyl group having 1 to 5 carbon atoms; 
         (b) 10 to 98% by weight, preferably 20 to 95% by weight, of one or more ethylenically unsaturated ester compounds of the formula (II) 
       
       
         
           
           
               
               
           
         
         wherein R is hydrogen or methyl, R 4  is a saturated or unsaturated linear or branched alkyl radical having 6 to 15 carbon atoms or a saturated or unsaturated cycloalkyl group having 6 to 15 carbon atoms, R 5  and R 6  are each independently hydrogen or a group of the formula —COOR″ in which R″ is hydrogen or a saturated or unsaturated linear or branched alkyl group having 6 to 15 carbon atoms; 
         (c) 0 to 30% by weight, preferably 5 to 20% by weight, of one or more ethylenically unsaturated ester compounds of the formula (III): 
       
       
         
           
           
               
               
           
         
         wherein R is hydrogen or methyl, R 7  is a saturated or unsaturated linear or branched alkyl radical having 16 to 40 preferably 16 to 30, carbon atoms or a cycloalkyl group having 16 to 40, preferably 16 to 30, carbon atoms, R 8  and R 9  are each independently hydrogen or a group of the formula —COOR′″ in which R′ is hydrogen or a saturated or unsaturated linear or branched alkyl group having 16 to 40, preferably 16 to 30, carbon atoms; 
         (d) 0 to 30% by weight of vinyl monomers; 
         (e) 2 to 10% by weight of at least one N-dispersant monomer. 
       
     
     
         8 . The lubricating oil composition of  claim 1 , wherein the non-dispersant ethylene-based olefin copolymer is an ethylene propylene copolymer. 
     
     
         9 . The lubricating oil composition of  claim 1 , wherein the magnesium from the magnesium containing detergent is from about 200 to about 850 ppm. 
     
     
         10 . A method of improving friction and reducing wear in an internal combustion engine comprising lubricating said engine with a lubricating oil composition having a HTHS viscosity at 150° C. in a range of about 1.3 to about 2.9 cP, comprising:
 a) a major amount of an oil of lubricating viscosity having a kinematic viscosity at 100° C. in a range of 1.5 to 6.0 mm 2 /s; 
 b) a dispersant polymethacrylate (DPMA) VII having a Mw of from 200,000 g/mol to 450,000 g/mol; 
 c) a non-dispersant ethylene-based olefin copolymer viscosity index improver having a Mw of from 50,000 g/mol to 150,000 g/mol and a total ethylene content of about 30 wt % to about 70 wt %; 
 d) from about 200 to about 1000 ppm of magnesium from a magnesium containing detergent; and
 wherein the lubricating oil composition is substantially free of molybdenum containing element. 
 
 
     
     
         11 . The method of  claim 10 , wherein the lubricating oil composition further comprises from 1 to 10 wt. %. of an ester base oil. 
     
     
         12 . The method of  claim 10 , wherein the magnesium containing detergent is a magnesium salicylate derived from a C 20 -C 24  isomerized normal alpha olefin. 
     
     
         13 . The method of  claim 10 , wherein the non-dispersant ethylene-based olefin copolymer viscosity index improver has a total ethylene content of about 55 to 65 wt. %. 
     
     
         14 . The method of  claim 10 , wherein the non-dispersant ethylene-based olefin copolymer viscosity index improver has a Mw of from 70,000 g/mol to 110,000 g/mol. 
     
     
         15 . The method of  claim 10 , wherein the a dispersant polymethacrylate (DPMA) VII have a Mw of from 200,000 g/mol to 300,000 g/mol. 
     
     
         16 . The method of  claim 10 , wherein the wherein the dispersant polymethacrylate VII comprises monomer units of:
 (a) 0 to 40% by weight of one or more ethylenically unsaturated ester compounds of the formula (I):   
       
         
           
           
               
               
           
         
         wherein R is hydrogen or methyl, R 1  is a saturated or unsaturated linear or branched alkyl radical having 1 to 5 carbon atoms or a saturated or unsaturated cycloalkyl group having 3 to 5 carbon atoms, R 2  and R 3  are each independently hydrogen or a group of the formula —COOR′ wherein R′ is hydrogen or a saturated or unsaturated linear or branched alkyl group having 1 to 5 carbon atoms; 
         (b) 10 to 98% by weight, preferably 20 to 95% by weight, of one or more ethylenically unsaturated ester compounds of the formula (II) 
       
       
         
           
           
               
               
           
         
         wherein R is hydrogen or methyl, R 4  is a saturated or unsaturated linear or branched alkyl radical having 6 to 15 carbon atoms or a saturated or unsaturated cycloalkyl group having 6 to 15 carbon atoms, R 5  and R 6  are each independently hydrogen or a group of the formula —COOR″ in which R″ is hydrogen or a saturated or unsaturated linear or branched alkyl group having 6 to 15 carbon atoms; 
         (c) 0 to 30% by weight, preferably 5 to 20% by weight, of one or more ethylenically unsaturated ester compounds of the formula (III): 
       
       
         
           
           
               
               
           
         
         wherein R is hydrogen or methyl, R 7  is a saturated or unsaturated linear or branched alkyl radical having 16 to 40 preferably 16 to 30, carbon atoms or a cycloalkyl group having 16 to 40, preferably 16 to 30, carbon atoms, R 8  and R 9  are each independently hydrogen or a group of the formula —COOR′″ in which R′″ is hydrogen or a saturated or unsaturated linear or branched alkyl group having 16 to 40, preferably 16 to 30, carbon atoms; 
         (d) 0 to 30% by weight of vinyl monomers; 
         (e) 2 to 10% by weight of at least one N-dispersant monomer. 
       
     
     
         17 . The method of  claim 10  wherein the non-dispersant ethylene-based olefin copolymer is an ethylene propylene copolymer. 
     
     
         18 . The method of  claim 10 , wherein the magnesium from the magnesium containing detergent is from about 200 to about 850 ppm.