Methods and compositions for reducing wear in internal combustion engines lubricated with a low phosphorous content borate-containing lubricating oil

Abstract

Disclosed are methods and lubricant compositions for reducing wear in internal combustion engines lubricated with a low phosphorous content lubricating oil. The lubricant compositions of this invention comprise a synergistic combination of a dispersed, hydrated, alkali metal borate and at least one phosphorous-containing compound wherein the total phosphorous employed in the composition is no more than about 0.08 weight percent based on the total weight of the composition.

1 . A lubricating oil composition comprising a major amount of an oil of lubricating viscosity, at least one oil-soluble, phosphorous-containing, anti-wear compound wherein the weight percent of total phosphorous in the composition is no more than about 0.08 weight percent based on the total weight of the composition; and an anti-wear effective amount of a dispersed, hydrated, alkali metal borate.  
   
   
       2 . The lubricating oil composition of  claim 1  wherein the total phosphorous in the composition is no more than 0.05 weight percent based on the total weight of the composition.  
   
   
       3 . The lubricating oil composition of  claim 1  wherein the oil-soluble, phosphorous-containing, anti-wear compound is selected from the group consisting of metal dithiophosphates, phosphorous esters, amine phosphates and amine phosphinates, sulfur-containing phosphorous esters, phosphoramides and phosphonamides.  
   
   
       4 . The lubricating oil composition of  claim 3  wherein said phosphorous esters are selected from the group consisting of phosphates, phosphonates, phosphinates, phosphine oxides, phosphites, phosphonites, phosphinites, and phosphines.  
   
   
       5 . The lubricating oil composition of  claim 3  wherein said sulfur-containing phosphorous esters are selected from the group consisting of phosphoro monothionate and phosphoro dithionates.  
   
   
       6 . The lubricating oil composition of  claim 3  wherein the oil-soluble, phosphorous-containing, anti-wear compound is a metal dithiophosphate.  
   
   
       7 . The lubricating oil composition of  claim 6  wherein the metal dithiophosphate is a zinc dialkyldithiophosphate.  
   
   
       8 . The lubricating oil composition of  claim 1  wherein the dispersed, hydrated, alkali metal borate is selected from the group consisting of dispersed, hydrated, sodium borates and dispersed, hydrated, potassium borates.  
   
   
       9 . The lubricating oil composition of  claim 8  wherein said dispersed, hydrated, alkali metal borate is a dispersed, hydrated, sodium borate.  
   
   
       10 . The lubricating oil composition of  claim 8  wherein said dispersed, hydrated, alkali metal borate is a dispersed, hydrated, potassium borate.  
   
   
       11 - 17 . (canceled)