The invention provides a fuel oil composition comprising a fuel oil of animal or vegetable origin and an additive comprising A) at least one copolymer of ethylene and 8-21 mol % of at least one acrylic or vinyl ester having a C.sub.1-C.sub.18-alkyl radical and B) at least one comb polymer containing structural units having C.sub.8-C.sub.16-alkyl radicals, the structural units being selected from C.sub.8-C.sub.16-alkyl (meth)acrylates, C.sub.8-C.sub.16-alkyl vinyl esters, C.sub.8-C.sub.16-alkyl vinyl ethers, C.sub.8-C.sub.16-alkyl (meth)acrylamides, C.sub.8-C.sub.16-alkyl allyl ethers and C.sub.8-C.sub.16-diketenes, where the sum R .times..times..times..times..times..times..times. ##EQU00001## is the molar average of the carbon chain length distributions in the alkyl radicals of the monomers B) is from 11.0 to 14.0, where m.sub.1, m.sub.2, . . . m.sub.g are the molar fractions of the abovementioned monomers B) in the polymer and the sum of the molar fractions m.sub.1 to m.sub.g=1, w.sub.1i, w.sub.1j . . . w.sub.2i, w.sub.2j . . . w.sub.gp are the proportions by weight of the individual chain lengths i, j, . . . p of the alkyl radicals of the different monomers B) 1 to g, and n.sub.1i, n.sub.1j . . . n.sub.2i, n.sub.2j . . . n.sub.gp are the chain lengths of the alkyl radicals i, j, . . . p of the monomers B) 1 to g.