Polymer combinations useful in distillate hydrocarbon oils to improve cold flow properties

A wax-containing distillate petroleum fuel oil boiling in the range of 120.degree. to 500.degree. C. and having a final boiling point above about 370.degree. C., which has been improved in its low temperature flow properties, containing in the range of about 0.001 to 0.5 wt. %, based on the weight of the total composition, of a synergistic flow improving combination of:

• a. aliphatic copolymer functioning as a nucleator for wax crystallization in said distillate, wherein said nucleator is a copolymer of ethylene and a vinyl ester of a C.sub.1 to C.sub.8 saturated aliphatic monocarboxylic acid, said copolymer having a (Mn) of from about 500 to 50,000 and in the range of 3 to 40 molar proportions of ethylene per molar proportion of said vinyl ester, and
• b. an aromatic oil soluble copolymer comprising principally C.sub.8 and C.sub.20 monovinyl aromatic monomer and ester of an ethylenically unsaturated acid selected from the group consisting of maleic anhydride, acrylic acid and methacrylic acid, esterified with a saturated, essentially straight chain alcohol having in the range of 6 to 22 carbon atoms, said aromatic copolymer having a number average molecular weight (Mn) in the range of about 500 to about 50,000, and the weight ratio of (a) to (b) is in the range of 1/20 to 5/1.