Mixed TBN detergents and lubricating oil compositions containing such detergents

Abstract

The present invention concerns a detergent additive for lubricating oil compositions comprising at least two of low, medium, and high TBN detergents. Preferably the detergent is a calcium salicylate. The present invention also concerns lubricating oil compositions comprising such detergents, and at least one of Group II base stock, Group III base stock, or wax isomerate base stock.

What is claimed is:  
     
         1 . A detergent additive for use in a lubricating oil composition comprising at least two of: 
 (a) a detergent having a TBN of over about 200,    (b) a detergent having a TBN between about 100 and 200; and    (c) a detergent having a TBN less than about 100.    
     
     
         2 . The detergent additive of  claim 1  wherein the detergent is a calcium salicylate detergent.  
     
     
         3 . The detergent additive of  claim 2  comprising each of (a), (b), and (c).  
     
     
         4 . A lubricating oil composition which comprises: 
 (a) an oil of lubricating viscosity; and    (b) at least two of: 
 (i) a detergent having a TBN of over about 200,  
 (ii) a detergent having a TBN between about 100 and 200; and  
 (iii) a detergent having a TBN less than about 100.  
   
     
     
         5 . The lubricating oil composition of  claim 4  where the detergent is a salicylate detergent.  
     
     
         6 . The lubricating oil composition of  claim 5  which comprises (i), (ii), and (iii).  
     
     
         7 . The lubricating oil composition of either  claim 4  or  claim 6  further comprising a hydrocarbyl aromatic fluid.  
     
     
         8 . The lubricating oil composition of  claim 7  wherein the salicylate detergent is a calcium salicylate.  
     
     
         9 . The lubricating oil composition of  claim 8  wherein the oil of lubricating viscosity has a viscosity index of about 110 or greater.  
     
     
         10 . The lubricating oil composition of  claim 9  wherein the oil of lubricating viscosity comprises at least one of Group II base stock, Group III base stocks, Group IV base stock, and wax isomerates, and mixtures thereof.  
     
     
         11 . The lubricating oil composition of  claim 10  wherein the wax isomerate base stock is a hydroisomerized Fischer-Tropsch wax.  
     
     
         12 . The lubricating oil composition of  claim 10  wherein the salicylates are each present in an amount of about 0.2 to about 4 weight percent of the lubricating oil composition on an active ingredient basis, and the hydrocarbyl aromatic fluid is present in an amount of about 3 to 30 weight percent of the lubricating oil composition.  
     
     
         13 . The lubricating oil composition of  claim 12  wherein the salicylates are each present in an amount of about 0.25 to about 2 weight percent of the lubricating oil composition on an active ingredient basis, and the hydrocarbyl aromatic fluid is present in an amount of about 4 to 20 weight percent of the lubricating oil composition.  
     
     
         14 . The lubricating oil composition of  claim 13  wherein at least 20 weight percent of the lubricating oil composition is comprised of at least one of Group II base stock, Group III base stock, and wax isomerate base stock.  
     
     
         15 . The lubricating oil composition of  claim 14  wherein at least 30 weight percent of the lubricating oil composition is comprised of at least one of Group II base stock, Group III base stock, and wax isomerate base stock.  
     
     
         16 . The lubricating oil composition of  claim 15  wherein at least 80 weight percent of the lubricating oil composition is comprised of at least one of Group II base stock, Group III base stock, or wax isomerate base stock.  
     
     
         17 . A method for improving the viscosity increase of a lubricating oil composition in a 3-hour Noack test comprising the step of adding to an oil of lubricating viscosity at least two of: 
 (i) a salicylate detergent having a TBN of over about 200,    (ii) a salicylate detergent having a TBN between about 100 and 200; and    (iii) a salicylate detergent having a TBN less than about 100.    
     
     
         18 . A method for improving piston cleanliness and ring sticking of a lubricating oil composition comprising the step of adding to an oil of lubricating viscosity at least two of: 
 (i) a salicylate detergent having a TBN of over about 200,    (ii) a salicylate detergent having a TBN between about 100 and 200; and    (iii) a salicylate detergent having a TBN less than about 100.