Additive compositions comprising: (i) at least one oil-soluble hydrogenated block diene polymer, comprising at least one crystallizable block, obtainable by end-to-end polymerization of a linear diene, and at least one non-crystallizable block, the non-crystallizable block being obtainable by 1,2-configuration polymerization of a linear diene, by polymerization of a branched diene, or by a mixture of such polymerizations, (ii) at least one ethylene-unsaturated ester compound; and (iii) at least one comb polymer. The additive compositions are used to improve cold flow characteristics in fuel oils. The additive compositions are particularly effective in fuel oils having a 90-20% boiling temperature range, as measured in accordance with ASTM D-86, of more than 115° C., preferably more than 120° C., more preferably more than 130° C., and most preferably more than 140° C., and a final boiling point of more than 370° C., preferably more than 380° C., and most preferably more than 390° C.