A lubricant additive concentrate having a kinematic viscosity of from about 40 to about 300 cSt at 100°C, containing a dispersant-detergent colloid mixture, including a polybutenyl succinimide dispersant that is the reaction product of a polyamine and polybutenyl succinic anhydride (PIBSA) derived from polybutene having a number average molecular weight (M n ) of from about 1300 to about 2500 and a terminal vinylidene content of at least about 65%, and succinic and/or maleic anhydride via an ene maleation process, the PIBSA having a succinic anhydride (SA) functionality (F) of greater than 1.7 and less than about 2.5; and a detergent colloid including overbased detergent having a total base number (TBN) of from about 370 to about 1000 mg KOH/g derived from one or more surfactants selected from (i) sulfonate; (ii) phenate; and (iii) carboxylate surfactant; in which the mass ratio of the dispersant to the overbased detergent colloid in the concentrate is from about 0.5 to about 5.0; and the dispersant and overbased colloidal together constitute at least 28 mass%, of the concentrate.