| abstract |
The present invention is directed to a lubricating oil composition, a diesel engine comprising a lubricating oil composition, and a method of lubricating a diesel engine provided with an exhaust gas recirculation system, comprising lubricating said engine with a lubricating oil composition comprising an oil of lubricating viscosity, and a polymeric N-dispersant booster comprising monomer units of: n na) 0 to 40 wt. % of one or more ethylenically unsaturated ester compounds of formula (I) n n wherein R is equal to H or CH 3 , R 1 represents a linear or branched alkyl group with 1 to 5 carbon atoms, R 2 and R 3 independently represent H or a group of the formula —COOR′, wherein R′ is H or an alkyl group with 1 to 5 carbon atoms, n nb) 10 to 98 wt. % of one or more ethylenically unsaturated ester compounds of formula (II) n n wherein R is equal to H or CH 3 , R 4 represents a linear or branched alkyl group with 6 to 15 carbon atoms, R 5 and R 6 independently represent H or a group of the formula —COOR″, wherein R″ is H or an alkyl group with 6 to 15 carbon atoms, n nc) 0 to 30 wt. % of one or more ethylenically unsaturated ester compounds of formula (III) n n wherein R is equal to H or CH 3 , R 7 represents a linear or branched alkyl group with 16 to 30 carbon atoms, R 8 and R 9 independently represent H or a group of the formula —COOR′″, wherein R′″ is H or an alkyl group with 16 to 30 carbon atoms, d) 0 to 30 wt. % vinyl monomers, e) 7 to 25 wt. % of at least one N— dispersant monomer, wherein a)-e) add up to 100 wt. %. |