Disclosed herein is a post-treated salt of a sulfurized alkyl-substituted hydroxyaromatic composition which is a reaction product of (a) a salt of a sulfurized alkyl-substituted hydroxyaromatic composition, wherein the alkyl-substituted hydroxyaromatic compound is derived from alkylation of a hydroxyaromatic compound with one or more olefins comprising C9 to C18 oligomers of monomers selected from propylene, butylene or mixtures thereof, (b) a source of an aldehyde and (c) a primary and/or secondary monoamine compound having at least one active hydrogen. The post-treated salt of a sulfurized alkylhydroxyaromatic composition disclosed herein has a reduced content of unsulfurized alkyl-substituted hydroxyaromatic compound and its unsulfurized metal salt as compared to the content, by combined mass, of the unsulfurized alkyl-substituted hydroxyaromatic compound and its unsulfurized metal salt present in the non-post-treated salt of a sulfurized alkyl-substituted hydroxyaromatic composition.