Oleaginous compositions

A composition comprising a middle distillate fuel oil containing 10 to 2000 ppm of an additive, effective to act as a wax crystal modifier and improve the filterability of the fuel, the additive consisting essentially of (i) a compound having the formula I, or a salt thereof:

• ##STR40## wherein B represents a polycyclic aromatic system selected from the group of naphthalene, anthracene, phenanthrene, pyrene, azulene, indene, hydroindene, fluorene, diphenylene, diphenyl, quinoline, indole, 2:3-dihydroindole, benzofuran, benzothiophen, carbazole, thiophenylamine, bisphenol A and fluorescein, A represents a hydrocarbyl group, R.sup.1 and R.sup.2 are the same or are different and each independently is an aliphatic group having 12-24 carbon atoms and being alkyl, alkylene, monoalkoxyalkyl or polyalkoxyalkyl or aliphatic groups which contain heteroatoms selected from O, N or S provided that one of R.sup.1 and R.sup.2 may represent a hydrogen atom, z is at least 2 and wherein the aromatic system carries at least one substituent group being either an hydroxyl or OC(O)CH.sub.3 group, and
• (ii) one or more cold flow improvers comprising a polar N compound, a comb polymer, a polyoxyalkylene ester, ether, ester/ether, amide/ester, an ethylene-unsaturated ester copolymer, a hydrocarbon polymer or a sulphur carboxy compound, provided that additive componenet (ii) is different from additive component (i).