Lubricating oil composition

A lubricating oil composition having a total base number of at least 15 mg KOH/g, as determined by ASTM D2896, the composition including:

• at least 40 mass % of an oil of lubricating viscosity;
• at least one overbased metal detergent;
• and
• at least one compound of formula (III):
• 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, acyloxyalkoxy, aryloxy, aryloxyalkyl, aryloxyalkoxy, 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 ZO— or Z(O(CR22)n′)y′X′—, wherein X′ is selected from the group consisting of (CR2′2)z, O and S;
• R2 and R2′ are each independently selected from H, C1 to C6 alkyl and aryl;
• z′ is 1 to 10;
• n′ is 0 to 10 when X′ is (CR2′2)Z′, and 2 to 10 when X′ is O or S;
• y′ is 1 to 30;
• Z is H, an acyl group, a polyacyl group, a lactone ester group, an acid ester group, an alkyl group or an aryl group;
• wherein one or more Y′ are groups Z(O(CR22)n′)y′X′— in which Z is derived from lactone ester of formula IV, acid ester of formula V, bisacyl of formula VI or a combination thereof;
• wherein R3, R4, R5, R6 R7, R8 and R9 are independently selected from H, alkyl and polyalkyl and polyalkenyl containing up to 200 C;
• R10 and R11 are independently selected from H, alkyl and polyalkyl and polyalkenyl containing up to 300 C;
• from about 2% to about 98% of the Y′ units are Z(O(CR22)2)y′O—, wherein Z is an acyl group and y′ is 1 to 6, and from about 98% to 2% of Y′ units are —OR2;
• m′ is 0 to 100;
• and p and s are each independently about 0 to about 25, with the proviso that p<m′;
• s<m′;
• and p+s>1.