An additive composition containing a polymer (A) and an anti-static additive (B).The polymer (A) has the following monomer components:(i) one or more compounds of formula (I) wherein R1 is hydrogen or CH3; and R2 is a hydrocarbon group having 6 to 30 carbon atoms and is a straight-chain or branched-chain alkyl group, or an aliphatic or aromatic cyclic group; (ii) one or more compounds of formula (II) wherein R1 has the meaning above and wherein R3 is hydrogen or C1-C22 alkyl; each R4 is independently hydrogen or C1-C22 alkyl; R5 is hydrogen, a substituted or unsubstituted aliphatic or aromatic cyclic group, or a substituted or unsubstituted straight-chain or branched-chain alkyl group having 1 to 22 carbon atoms; n=0 or an integer from 1 to 22; and m is an integer from 1 to 30; and (iii) one or more compounds of formula (III) wherein R6, R7, R8, R9 and R10 are each independently hydrogen, a straight-chain or branched-chain alkyl group having 1 to 20 carbon atoms which may be substituted or unsubstituted, hydroxyl, NH2, or wherein two or more of R6, R7, R8, R9 and R10 may together form an aliphatic or aromatic ring system, which ring system may be substituted or unsubstituted. The anti-static additive (B) is (iv) an olefin polysulfone and (v) a polymeric polyamine reaction product of epichlorohydrin and an aliphatic primary monoamine or an N-aliphatic hydrocarbyl alkylene diamine, or the sulfonic acid salt of the polymeric polyamine reaction product. The weight:weight ratio of the polymer (A) to the anti-static additive (B) in the additive composition is from about 1:1 to about 500:1.