Lubricating oil compositions with improved friction properties

Abstract

The present invention concerns friction reducers for use in lubricating oil compositions which comprise certain groups of aromatic compounds, esters, narrow mixtures of base stocks, and/or amorphous polymers such as amorphous olefin copolymers. These compositions can provide substantial reductions in the coefficient of friction and fuel economy improving benefits when admixed to lubricating oils without deleterious effects such as instability, undesirable high viscosities and deposits. In one aspect of the invention, pentaerythritol esters and optionally triol esters are added to lubricating oil compositions to provide reduced friction and improved fuel economy. In a second aspect of the invention, similar results are obtained by adding hydrocarbyl aromatics to a lubricating oil composition containing one or more of Groups II and III base stock. In a third aspect, the invention concerns a lubricating oil composition comprising an amorphous olefin copolymer and one or more of Groups II and III base stocks. In one embodiment, the third aspect also includes one or more of hydrocarbyl aromatics and polyol esters as part of the composition. In a forth aspect, moderate concentrations of hydrocarbyl aromatics are used in a lubricating oil composition comprising paraffinic base oil stocks and preferably a borated polyisobutenyl succinimide ashless dispersant.

1 . A lubricating composition comprising a mixture of: 
 (a) one or more base stocks selected from the group consisting of Group II base stock, Group III base stocks, and wax isomerates, and    (b) an amorphous olefin copolymer.    
     
     
         2 . A lubricating composition as in  claim 1  wherein said amorphous olefin copolymer is provided at about 1 wt % to about 20 wt %.  
     
     
         3 . A lubricating composition as in  claim 2  further comprising a member selected from the group consisting of esters, hydrocarbyl aromatics, and mixtures thereof.  
     
     
         4 . A lubricating composition as in  claim 3  wherein said member comprises about 1 wt % to about 30 wt % of the lubricating composition.  
     
     
         5 . A lubricating composition as in  claim 3  further comprising a borated hydrocarbyl-substituted succinimide wherein the hydrocarbyl group has a M n  from about 1000 to about 5000 and is present at about at least 0.3 wt % active ingredient.  
     
     
         6 . A lubricating composition as in  claim 5  wherein said borated hydrocarbyl-substituted succinimide comprises borated hydrocarbyl-substituted mono- and bis-succinimides.