A composition comprising a hydrocarbon polymer having {overscore (M)}n ranging from 20,000 to about 500,000, when the polymer is not a star polymer, and up to about GPC peak molecular weight of 4,000,000 when the polymer is a star polymer having attached thereto pendant groups Aa and Bb wherein each A is independently a member of the group of formula —Q—Kk wherein each Q is independently an aliphatic or aromatic hydrocarbon group, each K is independently a member selected from the group consisting of amide groups, nitrile groups, ester groups and carboxylic acid groups, and each k is independently a number ranging from 1 to about 3, and when k≧2, groups —K on adjacent carbon atoms, taken together, may constitute a succinimide group, and a is 0 or a number ranging from 1 to about 50; and each B is independently a member of the group of formula: wherein each X is independently O, S, or NRb, each Rb is independently H, NH2, hydrocarbyl, hydroxyhydrocarbyl, or aminohydrocarbyl, each s is independently 1 or 2, and each Z is independently a hydrocarbyl group, optionally substituted with one or more carboxylic acid groups or amide groups, each Ra is independently an ethylene group, a propylene group, which groups optionally have hydrocarbyl or hydroxyhydrocarbyl substituents, or wherein J is H, SH, NH2, or OH, and tautomers thereof; and b is a number ranging from 1 to about 50 with the proviso that when X is O, then b ranges from 2 to about 50.