Additive combinations and fuels containing them

A wax-containing petroleum fuel oil comprising a major proportion of a distillate oil boiling in the range of 120.degree. to 500.degree. C., which fuel oil 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 flow improving combination of:

• (A) one part by weight of an oil-soluble ethylene backbone distillate flow improving polymer having a number average molecular weight in the range of about 500 to 50,000 which is a copolymer consisting essentially of 3 to 40 molar proportions of ethylene per molar proportion of unsaturated ester of the general formula:
• ##STR4## wherein R.sub.1 is methyl or hydrogen, R.sub.2 is --OOCR.sub.4 or --COOR.sub.4 where R.sub.4 is a C.sub.1 to C.sub.28 alkyl group and R.sub.3 is hydrogen or --COOR.sub.4 ;
• (B) 0.1 to 10 parts by weight of an oil soluble hydrocarbon polymer having a number average molecular weight in the range of 10.sup.3 to 10.sup.6 selected from the group consisting of:
• copolymers comprising about 15 to 90 wt.% ethylene and 10 to 85 wt.% C.sub.3 to C.sub.30 olefin;
• hydrogenated polymer consisting essentially of styrene or alkylated styrene with conjugated diene selected from the group consisting of butadiene, isoprene, piperylene and 2,3-dimethyl butadiene, or mixtures thereof;
• polymers consisting essentially of polyisobutylene;
• hydrogenated conjugated diene polymers consisting essentially of 1,3-butadiene, isoprene, 1,3-pentadiene, or 1,3-dimethyl butadiene, or mixtures thereof;
• and
• (C) 0.1 to 10 parts by weight of polar oil soluble compound selected from the group consisting of:
• (1) oil soluble nitrogen compounds containing a total of 30 to 300 carbon atoms and having at least one straight chain alkyl segment of 8 to 40 carbons and selected from the class consisting of amine salts and/or amides of hydrocarbyl carboxylic acids or anhydrides having 1 to 4 carbonyl groups;
• and
• (2) compounds, other than (1) above, of the formula RX wherein R is an oil solubilizing hydrocarbon group of 8 to 150 carbon atoms and X is selected from the group consisting of carboxylate, sulfonate, sulphate, phosphate, phenate, and borate groups.