A fuel composition comprising a distillate fuel oil and a wax crystal modifier of a derivative of (1) a monocyclic compound having at least 7 ring atoms or of (2) a polycyclic compound, said derivative comprising two substituents attached to adjoining ring atoms in the ring of derivative (1) or in one of the rings of derivative (2). One of said substituents is an amide or a salt of a secondary amine and the other of said substituents is an amide of a primary or secondary amine, a salt of a primary, secondary or tertiary amine, a quaternary ammonium salt or an ester, each substituent containing at least one hydrogen- and carbon-containing group of at least 10 carbon atoms. |