Nitrogen-containing cold flow improvers for middle distillates

Claim 1

A fuel oil composition comprising a major amount of a middle distillate fuel oil, and a cold flow improving synergistic mixture of: A. in the range of about 0.005 to 0.5 weight percent of a nitrogen compound selected from the group consisting of: a. N,N-dialkyl n-alkane amides of the formula ##EQU4##wherein R is a C 1 to C 30 alkyl group, and R 1 and R 2 are each C 8 to C 24 straight chain alkyl groups; and b. C 4 to C 10 hydrocarbyl aliphatic dicarboxylic acid wherein one of said carboxylic acid groups is reacted with either C 14 to C 36 aliphatic hydrocarbyl alcohol or a secondary alkyl monoamine having C 10 to C 24 straight chain alkyl groups, to thereby form a monoester or a monoamide, and the other of said carboxylic acid groups is reacted to form an amide or salt with a secondary alkyl monoamine having C 10 to C 24 straight chain alkyl groups; and at least one other additive selected from the group consisting of: B. in the range of 0.002 to 0.2 weight percent of an ethylene backbone pour point depressant which is a copolymer of 4 to 20 molar proportions of ethylene and molar proportion of unsaturated ester of the general formula: ##EQU5##wherein R 1 is hydrogen or methyl, and R 2 is a --OOCR 4 or --COOR 4 group wherein R 3 is hydrogen or --COOR 4 and R 4 is hydrogen or a C 1 to C 16 alkyl group, said copolymer having a number average molecular weight in the range of about 1,000 to 50,000; and/or C. in the range of about 0.005 to 0.30 weight percent of waxy material selected from the group consisting of: a. amorphous hydrocarbon fraction having a number average molecular weight of about 600 to 3000, a melting point in the range of about 25° to 60° C., and having no more than about 5 weight percent of normal paraffins; b. alkylated aromatic formed by reacting paraffins of about 12 to about 50 carbon atoms, chlorinated to about 5 to 25 weight percent chlorine, with an aromatic hydrocarbon selected from the group consisting of phenol and naphthalene; and c. microcrystalline wax.