Michael adduct amino esters as total base number boosters for marine diesel engine lubricating compositions

A lubricating composition comprising an oil of lubricating viscosity, an overbased metal-containing detergent, and an amino carboxylate compound of formula (I):

• NR1R2—((CHR3)xNR4)n—(CHR5)2—COY, (I)
• where,
• R1 and R2 are independently selected from (CHR6)2—COY′, H, and C1-C3 alkyl and wherein at least one of R1 and R2 is (CHR6)2—COY′;
• or wherein NR1R2 is an optionally substituted heterocyclic structure containing nitrogen and an additional hetero atom selected from oxygen and nitrogen;
• Y and Y′ are independently selected from —OR7, —NHR7, and —N(R7)2;
• each R7 is independently selected from C6-C12 alkyl and C6-C12 alkenyl;
• R3, R5 and R6 are independently selected from H and C1-C4 alkyl;
• R4 is selected from H, C1-C4 alkyl, and (CHR3)x(NH2;
• x is from 2 to 4;
• and
• n is at least 1, except where NR1R2 is a heterocyclic structure, where n is at least 0.