A post-treated polymeric dispersant which comprises reacting (I) a post-treating agent selected from a cyclic carbonate, a linear mono-carbonate, a linear poly-carbonate, an aromatic polycarboxylic acid or an aromatic polycarboxylic anhydride or an aromatic polycarboxylic acid ester and (II) an oil-soluble lubricating oil additive composition prepared by the process which comprises reacting a copolymer, with at least one ether compound and with at least one aliphatic compound capable of reacting with at least one monocarboxylic acid or ester thereof, or dicarboxylic acid, anhydride or ester thereof.