Lubricating oil compositions

Abstract

The present invention provides a viscosity index improving lubricant additive which comprises an olefinic oligomer of about 2,000 to about 20,000 number average molecular weight having a viscosity of 75 to about 3,000 cSt at 100° C. and a hydrocarbyl aromatic which contains at least about 5% of its weight from aromatic moieties having a viscosity of about 3 to about 50 cSt at 100° C. where the weight ratio of hydrocarbyl aromatic component to olefin oligomer is from about 1:2 to about 50:1. In another aspect, the invention provides for a lubricating oil composition comprising a base oil and the instant viscosity index improving additive.

What is claimed is:  
     
         1 . Lubricant additive comprising: 
 (a) a hydrocarbyl aromatic which contains at least about 5% of its weight from aromatic moieties and having a viscosity of about 3 to about 50 cSt at 100° C.;    (b) an olefinic oligomer of about 2,000 to about 20,000 number average molecular weight and having a viscosity of about 75 to about 3,000 cSt at 100° C.; and    wherein the weight ratio of component (a) to component (b) is from about 1:2 to about 50:1.    
     
     
         2 . The lubricant additive of  claim 1  wherein the olefinic oligomer is an alpha olefin.  
     
     
         3 . The lubricant additive of  claim 2  wherein the alpha olefin has a viscosity of about 100 to about 1,500 cSt at 100° C.  
     
     
         4 . The lubricant additive of  claim 3  wherein the hydrocarbyl aromatic has a viscosity of about 3.4 to about 20 cSt at 100° C.  
     
     
         5 . The lubricant additive of  claim 4  wherein the ratio of component (a) to component (b) is from about 1.5:1 to about 10:1.  
     
     
         6 . The lubricant additive of  claim 5  wherein the alpha olefin is derived from decene, dodecene, tetradecene, or octane.  
     
     
         7 . The lubricant additive of  claim 6  wherein the hydrocarbyl aromatic contains an aromatic moiety of the group consisting of: alkyl benzenes, alkyl naphthalenes, alkyl diphenyl oxides, alkyl naphthols, alkyl diphenyl sulfides, and alkylated bis-phenol A wherein the alkylated aromatic can be mono-alkylated, dialkylated or polyalkylated.  
     
     
         8 . The lubricant additive of  claim 7  wherein the alpha olefin has a viscosity of about 100 to about 1,000 cSt at 100° C.  
     
     
         9 . A lubricating oil composition comprising: 
 (a) an oil of lubricating viscosity selected from the group consisting of Group II base stock, Group III base stock, Group IV base stock, and wax isomerates, and mixtures thereof; and    (b) the lubricant additive of  claim 1  in an amount of about 3% to about 40% of the weight of the lubrication oil composition.    
     
     
         10 . A lubricating oil composition comprising: 
 (a) an oil of lubricating viscosity selected from the group consisting of Group II base stock, Group III base stock, Group IV base stock, and wax isomerates, and mixtures thereof; and    (b) the lubricant additive of  claim 2  in an amount of about 3 to about 40% of the weight of the lubrication oil composition.    
     
     
         11 . A lubricating oil composition comprising: 
 (a) an oil of lubricating viscosity selected from the group consisting of Group II base stock, Group III base stock, Group IV base stock, and wax isomerates, and mixtures thereof; and    (b) the lubricant additive of  claim 8  in an amount of about 3 to about 40% of the weight of the lubrication oil composition.    
     
     
         12 . The lubricating oil composition of any one of claims  9 - 11  wherein the oil of lubricating viscosity contains at least 50 weight percent of at least one of Group II base stock, Group III base stocks, Group IV base stock, and wax isomerates, and mixtures thereof.  
     
     
         13 . The lubricating oil composition of  claim 12  wherein the amount of Group II base stock, Group III base stocks and wax isomerate base stock is at least 20 weight percent of the lubricating oil composition.  
     
     
         14 . The lubricating oil composition of  claim 13  wherein the amount of Group II base stock, Group III base stocks and wax isomerate base stock is at least 30 weight percent of the lubricating oil composition.  
     
     
         15 . The lubricating oil composition of  claim 14  wherein the amount of Group II base stock, Group III base stocks and wax isomerate base stock is at least 50 weight percent of the lubricating oil composition.  
     
     
         16 . A method of obtaining viscosity index enhancement in a lubrication composition comprising the step of adding the following to the lubricating composition: 
 (i) a hydrocarbyl aromatic which contains at least about 5% of its weight from aromatic moieties and having a viscosity of about 3 to about 50 cSt at 100° C.; and    (ii) an olefinic oligomer of about 2,000 to about 20,000 number average molecular weight and having a viscosity of about 75 to about 3,000 cSt at 100° C.;    wherein the weight ratio of component (a) to component (b) is from about 1:2 to about 50: 1.    
     
     
         17 . A method of obtaining enhanced high-temperature high-shear (HTHS) viscosity performance of a lubricating composition comprising the step of adding the following to the lubricating composition: 
 (i) a hydrocarbyl aromatic which contains at least about 5% of its weight from aromatic moieties and having a viscosity of about 3 to about 50 cSt at 100° C.; and    (ii) an olefinic oligomer of about 2,000 to about 20,000 number average molecular weight and having a viscosity of about 75 to about 3,000 cSt at 100° C.;    wherein the weight ratio of component (a) to component (b) is from about 1:2 to about 50:1.    
     
     
         18 . A method of making lubricant composition rheological properties more Newtonian comprising the step of adding the following to the lubricating composition: 
 (i) a hydrocarbyl aromatic which contains at least about 5% of its weight from aromatic moieties and having a viscosity of about 3 to about 50 cSt at 100° C.; and    (ii) an olefinic oligomer of about 2,000 to about 20,000 number average molecular weight and having a viscosity of about 75 to about 3,000 cSt at 100° C.;    wherein the weight ratio of component (a) to component (b) is from about 1:2 to about 50:1.