In another embodiment of the present invention, the copolymer reactant is a copolymer obtained by reacting (a) at least one monoethylenically unsaturated C3-C28 monocarboxylic acid or ester thereof, or a C4-C28 dicarboxylic acid, anhydride or ester thereof and (b) at least one copolymerizable polymer composed of at least 3 olefin molecules of propene or of a branched 1-olefin of from about 4 to ab