Lubricant composition for combustion engine containing dispersant additive and polymer dispersant viscosity index improver

Abstract

A multigrade lubricating oil composition with enhanced anti-wear properties for use in an internal combustion engine comprises (a) a base oil comprising at least 90% by weight of the base oil, of one or more basestocks selected from the group consisting of base stocks derived from Fischer-Tropsch synthesised, waxy, paraffinic hydrocarbon material by processes comprising hydrocracking and/or hydroisomerisation, Group II basestocks, Group III basestocks and mixtures thereof; (b) one or more dispersant viscosity modifiers in a total amount of 0.15 to 0.8% by weight of the composition; (c) one or more dispersants in a total amount of active dispersants of 1.5 to 3% by weight of the composition; (d) one or more detergents; and (e) one or more metal dihydrocarbyl dithiophosphates.

1 .- 10 . (canceled) 
   
   
       11 . A multigrade lubricating oil composition for use in an internal combustion engine 
     which composition comprises:
 (a) a base oil comprising at least 90% by weight of the base oil, of one or more basestocks selected from the group consisting of base stocks derived from Fischer-Tropsch synthesised, waxy, paraffinic hydrocarbon material by processes comprising hydrocracking and/or hydroisomerisation, Group II basestocks, Group III basestocks and mixtures thereof; 
 (b) one or more dispersant viscosity modifiers in a total amount of 0.15 to 0.8% by weight of the composition; 
 (c) one or more dispersants in a total amount of active dispersants of 1.5 to 3% by weight of the composition; 
 (d) one or more detergents; and 
 (e) one or more metal dihydrocarbyl dithiophosphates. 
 
   
   
       12 . A composition as claimed in  claim 11  in which the one or more detergents are present in the lubricating oil composition in a total active concentration of 1 to 5% by weight of the composition. 
   
   
       13 . A composition as claimed in  claim 11  in which the one or more metal dihydrocarbyl dithiophosphates are present in the lubricating oil composition in a total amount, expressed as phosphorus, of 0.01 to 0.2% by weight of the composition. 
   
   
       14 . A composition as claimed in  claim 12  in which the one or more metal dihydrocarbyl dithiophosphates are present in the lubricating oil composition in a total amount, expressed as phosphorus, of 0.01 to 0.2% by weight of the composition. 
   
   
       15 . Use in a multigrade lubricating oil composition comprising one or more dispersants in a total amount of active dispersants of 1.5 to 3% by weight of the composition, one or more detergents and one or more metal dihydrocarbyl dithiophosphates, of
 (i) one or more dispersant viscosity modifiers in a total amount of 0.15 to 0.8% by weight of the composition, in combination with   (ii) a base oil comprising at least 90% by weight of the base oil, of one or more basestocks selected from the group consisting of base stocks derived from Fischer-Tropsch synthesised, waxy, paraffinic hydrocarbon material by processes comprising hydrocracking and/or hydroisomerisation, Group II basestocks, Group III basestocks and mixtures thereof, to enhance the anti-wear properties of the lubricating oil composition.   
   
   
       16 . Use as claimed in  claim 15  in which the use enhances the anti-wear properties with respect to valve train wear of an internal combustion engine. 
   
   
       17 . Use as claimed in  claim 16  in which the internal combustion engine is a diesel engine. 
   
   
       18 . Use as claimed in  claim 17  in which the internal combustion engine is a heavy duty diesel engine. 
   
   
       19 . A method of reducing the valve train wear of an internal combustion engine which method comprising lubricating the engine with a multigrade lubricating oil composition as claimed in  claim 11 . 
   
   
       20 . A method as claimed in  claim 19  in which the internal engine is a diesel engine. 
   
   
       21 . A method as claimed in  claim 20  in which the internal engine is a heavy duty diesel engine. 
   
   
       22 . A method as claimed in  claim 19  which method comprising lubricating the engine with a multigrade lubricating oil composition. 
   
   
       23 . A method as claimed in  claim 22  in which the internal engine is a diesel engine. 
   
   
       24 . A method as claimed in  claim 23  in which the internal engine is a heavy duty diesel engine. 
   
   
       25 . A method as claimed in  claim 19  which method comprising lubricating the engine with a multigrade lubricating oil composition. 
   
   
       16 . A method as claimed in  claim 25  in which the internal engine is a diesel engine. 
   
   
       27 . A method as claimed in claim  26  in which the internal engine is a heavy duty diesel engine. 
   
   
       28 . A method as claimed in  claim 19  which method comprising lubricating the engine with a multigrade lubricating oil composition. 
   
   
       29 . A method as claimed in  claim 28  in which the internal engine is a diesel engine. 
   
   
       30 . A method as claimed in  claim 29  in which the internal engine is a heavy duty diesel engine.