Disclosed is a process for preparing a molybdated succinimide complex, the process comprising: (a) reacting an alkyl or alkenyl succinimide of a polyamine of formula I or formula II or mixtures thereof: wherein R is an about C12 to C30 alkyl or alkenyl group, R′ is a straight or branched-chain alkylene group having 2 to 3 carbon atoms, x is 1 to 11, and y is 1 to 10, with an α,β-unsaturated mono-carboxylic acid or carboxylic acid ester, in a charge mole ratio of the α,β-unsaturated mono-carboxylic acid or carboxylic acid ester to the succinimide of formula I or formula II or mixtures thereof of about 0.1:1 to about 6:1, and wherein the reaction temperature is no greater than about 135° C.; and (b) reacting the succinimide product of step (a) with an acidic molybdenum compound to provide the molybdated succinimide complex, wherein the molybdated succinimide complex prepared is a liquid at room temperature.