Lubricating Oil Composition

Abstract

A lubricating oil composition having a phosphorus content of up to 0.12 wt %, a sulfated ash content of up to 1.2 wt % comprising (a) a major amount of an oil of lubricating viscosity; (b) an alkali metal or alkaline earth metal alkyl salicylate lubricating oil detergent providing from 7-15 mmol salicylate soap per kilogram of lubricating oil composition; (c) one or more dispersants providing the lubricating oil composition with from at least 0.12 wt % to 0.20 wt % atomic nitrogen, based on the weight of the lubricating oil composition, and (d) a dispersant-viscosity modifier.

1 . A lubricating oil composition having a phosphorus content of up to 0.12 wt % and a sulfated ash content of up to 1.2 wt % comprising:
 (a) a major amount of an oil of lubricating viscosity;   (b) an alkali metal or alkaline earth metal alkyl salicylate lubricating oil detergent providing from about 7 to about 15 mmol salicylate soap per kilogram of lubricating oil composition;   (c) one or more ashless, nitrogen-containing dispersants providing the lubricating oil composition with from at least about 0.12 wt % to about 0.20 wt % atomic nitrogen, based on the weight of the lubricating oil composition, and   (d) a dispersant-viscosity modifier.   
     
     
         2 . A lubricating oil composition according to  claim 1 , wherein the phosphorous content is no more than 0.08 wt %. 
     
     
         3 . A lubricating oil composition according to  claim 1 , wherein the sulfated ash content is no more than 1.0 wt %. 
     
     
         4 . A lubricating oil composition according to  claim 1 , wherein the alkali metal or alkaline earth metal alkyl salicylate lubricating oil detergent providing from about 8 to about 11 mmol salicylate soap per kilogram of lubricating oil composition. 
     
     
         5 . A lubricating oil composition according to  claim 1 , wherein the one or more dispersants provide the lubricating oil composition with from at least about 0.12 wt % to about 0.17 wt % atomic nitrogen, based on the weight of the lubricating oil composition. 
     
     
         6 . A lubricating oil composition according to  claim 1 , wherein the alkali metal or alkaline earth metal alkyl salicylate is calcium or magnesium salicylate or a combination thereof. 
     
     
         7 . A lubricating oil composition according to  claim 1 , further comprising an alkaline earth metal alkyl sulphonate lubricating oil detergent. 
     
     
         8 . A lubricating oil composition according to  claim 1 , wherein the dispersant is a polyisobutenyl succinimide dispersant. 
     
     
         9 . A lubricating oil composition according to  claim 1  which meets the requirements of both the API-CJ4 specification and the ACEA E6 specification. 
     
     
         10 . A method of lubricating a vehicle engine comprising an exhaust gas recirculation (EGR) system comprising use in that engine of a lubricating oil composition according to  claim 1 . 
     
     
         11 . A method according to  claim 10 , wherein the engine is a compression ignition engine. 
     
     
         12 . A method according to  claim 11 , wherein the engine is a heavy duty diesel engine. 
     
     
         13 . A method according to  claim 10 , wherein the engine further comprises a selective catalytic reduction device.