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

Claim 1

A wax-containing distillate petroleum fuel oil boiling in the range of 120° to 500° C. and having a final boiling point above about 370° 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 1 to C 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 8 and C 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.