Engine Lubrication

Abstract

A trunk piston or cross-head diesel engine having a centrifuge system including a sealing medium is lubricated with a lubricant which, for the cross-head engine, is a system lubricant and which contains 0.04 to 5 mass %, expressed as active ingredient, of a combination of one or more linked aromatic compounds and one or more nitrogen containing ashless disperants, in a mass:mass ratio in the range of 1:3 to 9:1.

1 . A method of lubricating a trunk piston or cross-head diesel engine having a centrifuge system including a sealing medium comprising operation of the engine and lubrication of the trunk piston engine or system lubrication of the cross-head engine with a lubricating oil composition comprising, or made by admixing:
 (A) an oil of lubricating viscosity, in a major amount; and   (B) from 0.04 to 5 mass %, expressed as active ingredient, of the lubricating oil of a combination of:
 (B1) at least one linked aromatic compound of the formula: 
   
       
         
           
           
               
               
           
         
         
           wherein: 
           each Ar independently represents an aromatic moiety having 0 to 3 substituents selected from the group consisting of alkyl, alkoxy, alkoxyalkyl, hydroxy, hydroxyalkyl, acyloxy, acyloxyalkyl, aryloxy, aryloxy alkyl, halo and combinations thereof; 
           each L is independently a linking moiety comprising a carbon-carbon single bond or a linking group; 
           each Y′ is independently a moiety of the formula Z(O(CR 2 ) n ) y X—, wherein X is selected from the group consisting of (CR′ 2 ) z , O and S; R and R′ are each independently selected from H, C 1  to C 6  alkyl and aryl; 
           z is 1 to 10; n is 0 to 10 when X is (CR′ 2 ) z , and 2 to 10 when X is O or S; y is 1 to 30; Z is H, an acyl group, an alkyl group or aryl group; 
           each a is independently 0 to 3, with the proviso that at least one Ar moiety bears at least one group Y′ in which Z is not H; and 
           m is 1 to 100, and 
           (B2) at least one nitrogen-containing dispersant, where the mass:mass ratio of (B1) to (B2) is in the rage from 1:3 to 9:1. 
         
       
     
     
         2 . A method as claimed in  claim 1 , wherein said mass:mass ratio of (B1) to (B2) is in the range of from 1:1 to 6:1. 
     
     
         3 . A method as claimed in  claim 2 , wherein said mass:mass ratio of (B1) to (B2) is in the range of from 3:1 to 6:1. 
     
     
         4 . A method as claimed in  claim 1 , wherein Y′ is Z(O(CR 2 ) 2 )yO—, Z is an acyl group and y is 1 to 6. 
     
     
         5 . A method as claimed in  claim 4 , wherein Ar is naphthalene, Y′ is ZOCH 2 CH 2 O—, Z is an acyl group and L is CH 2 . 
     
     
         6 . A method as claimed in  claim 5 , wherein Ar is derived from 2-(2-naphthyloxy)-ethanol and m is 2 to 25. 
     
     
         7 . A method as claimed in  claim 6 , wherein Z is derived from a polyalkyl or polyalkenyl succinic acylating agent having  M   n  of from about 100 to about 5000. 
     
     
         8 . A method as claimed in  claim 6 , wherein Z is derived from hydrocarbyl isocyanate. 
     
     
         9 . A method as claimed in  claim 1 , wherein the nitrogen-containing dispersant is a polybutenyl polyalkyleneamine succinimide derived from polybutene having an  M   n  of from 900 to 2500. 
     
     
         10 . A method as claimed in  claim 1 , wherein the lubricating oil composition comprises one or more overbased calcium salicylate detergent additives and has a total base number of at least 15 mg KOH/g, as determined by ASTM D2896. 
     
     
         11 . A method as claimed in  claim 1 , wherein the sealing medium is water. 
     
     
         12 . A method of enhancing the water-shedding properties, as measured by a centrifuge water shedding test, of a lubricating oil composition in the lubrication of a trunk piston engine or the system lubrication of cross-head diesel engine by employing a lubricating oil composition as defined in  claim 1  when compared with a corresponding lubricating oil composition where (B) contains only (B2). 
     
     
         13 . A method as claimed in  claim 12 , wherein the sealing medium is water. 
     
     
         14 . A trunk piston or cross-head diesel engine lubricating oil composition having a total base number of at least 15 mg KOH/g, as determined by ASTM D2896, comprising:
 (A) at least 40 mass % of an oil lubricating viscosity; and   (B) from 0.04 to 5 mass %, expressed as active ingredient, of the lubricating oil of a combination of:
 (B1) at least one linked aromatic compound of the formula: 
   
       
         
           
           
               
               
           
         
         
           wherein: 
           each Ar independently represents an aromatic moiety having 0 to 3 substituents selected from the group consisting of alkyl, alkoxy, alkoxyalkyl, hydroxy, hydroxyalkyl, acyloxy, acyloxyalkyl, aryloxy, aryloxy alkyl, halo and combinations thereof; 
           each L is independently a linking moiety comprising a carbon-carbon single bond or a linking group; 
           each Y′ is independently a moiety of the formula Z(O(CR 2 ) n ) y X—, wherein X is selected from the group consisting of (CR′ 2 ) z , O and S; R and R′ are each independently selected from H, C 1  to C 6  alkyl and aryl; 
           z is 1 to 10; n is 0 to 10 when X is (CR′ 2 ) z , and 2 to 10 when X is O or S; y is 1 to 30; Z is H, an acyl group, an alkyl group or an aryl group; 
           each a is independently 0 to 3, with the proviso that at least one Ar moiety bears at least one group Y′ in which Z is not H; and 
           m is 1 to 100, and 
           (B2) at least one nitrogen-containing dispersant, where the mass:mass ratio of (B1) to (B2) is in the range from 1:3 to 9:1. 
         
       
     
     
         15 . The lubricating oil composition as claimed in  claim 14 , wherein said mass:mass ratio of (B1) to (B2) is in the range from 1:1 to 6:1. 
     
     
         16 . The lubricating oil composition as claimed in  claim 15 , wherein said mass:mass ratio of (B1) to (B2) is in the range from 3:1 to 6:1. 
     
     
         17 . The lubricating oil composition as claimed in  claim 14 , wherein Y′ is Z(O(CR 2 ) 2 )yO—, Z is an acyl group and y is 1 to 6. 
     
     
         18 . The lubricating oil composition as claimed in  claim 17 , wherein Ar is naphthalene, Y′ is ZOCH 2 CH 2 O—, Z is an acyl group and L is CH 2 . 
     
     
         19 . The lubricating oil composition as claimed in  claim 18 , wherein Ar is derived from 2-(2-naphthyloxy)-ethanol and m is 2 to 25. 
     
     
         20 . The lubricating oil composition as claimed in  claim 19 , wherein Z is derived from a polyalkyl or polyalkenyl succinic acylating agent having  M   n  of from about 100 to about 5000. 
     
     
         21 . The lubricating oil composition as claimed in  claim 19 , wherein Z is derived from hydrocarbyl isocyanate. 
     
     
         22 . The lubricating oil composition as claimed in  claim 14 , wherein the nitrogen-containing dispersant is a polybutenyl polyalkyleneamine succinimide derived from polybutene having an  M   n  of from 900 to 2500. 
     
     
         23 . The lubricating oil composition as claimed in  claim 14 , further comprising one or more overbased calcium salicylate detergent additives. 
     
     
         24 . The lubricating oil composition as claimed in  claim 14 , having a total base number of at least 20 mg KOH/g, as determined by ASTM D2896.