Fuel oil additives and compositions

1. A middle distillate fuel oil composition comprising fuel oil boiling in the range of from 100° C. to 500° C. and a copolymer comprising:

(A) either:

(i) an olefin; or

(ii) a mixture of olefins; and

(B) an ethylenically unsaturated compound selected from the group consisting of acrylic acid, methylacrylic acid, fumaric acid, maleic acid and maleic anhydride;

wherein the olefin or mixture of olefins carry hydrocarbyl substituents containing a continuous chain of carbon atoms, and optionally oxygen and/or nitrogen and/or sulfur atoms; the average length of the chains being at least 22 atoms; and wherein the copolymer is derivatized with an amine selected from the group consisting of n-octyl amine, n-hexyl amine, n-butyl amine and n-propyl amine, said derivatization being carried out after preparation of the copolymer.

2. The composition of claim 1 wherein the continuous chain is an alkylene chain.

3. The composition of claim 1 wherein (A) is an alpha-olefin.

4. The composition of claim 3 the alpha-olefin is linear.

5. The composition of claim 1 wherein the continuous chain is an alkylene chain.

6. The composition of claim 1 wherein (A) is a mixture of linear alpha-olefins containing 30 or more carbon atoms, or a mixture of linear alpha-olefins containing from 24 to 28 carbon atoms.

7. The composition of claim 1 further comprising another fuel additive selected from the group consisting of:

(a) polyoxyalkylene esters, ethers, ester/ethers or mixtures thereof;

(b) ethylene unsaturated ester copolymers and/or terpolymers;

(c) polar nitrogen containing compounds;

(d) sulfur carboxy compounds; and

(e) hydrocarbon polymers.

8. The middle distillate fuel oil composition of claim 1 wherein the copolymer is present in an amount of from 1 to 5000 ppm based on the weight of the composition.

9. The middle distillate fuel oil composition of claim 1 wherein the fuel oil contains up to 10 wt. % wax at 10° C. below wax appearance temperature.