Additive compositions and to fuel oils

An additive composition comprises a polymer (A) and a condensation product (B). Polymer (A) comprises the following monomer components: (i) one or more compounds of formula (I) wherein R 1 is hydrogen or CH 3 ; and R 2 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 R 1 has the meaning above and wherein R 3 is hydrogen or C 1 - C 22 alkyl; each R 4 is independently hydrogen or C 1 - C 22 alkyl; R 5 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 R 6 , R 7 , R 8 , R 9 and R 10 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, NH 2 , or wherein two or more of R 6 , R 7 , R 8 , R 9 and R 10 may together form an aliphatic or aromatic ring system, which ring system may be substituted or unsubstituted. Condensation product (B) comprises the product formed by the reaction of an aliphatic aldehyde or ketone, or a reactive equivalent, with a substituted phenol or mixture of substituted phenols.