An additive composition for blending with fuel, the additive composition at least 3% w/w of a viscosity index (VI) improving polymer; and a solvent mixture including in the range of from 10 to 85% v/v of a middle distillate gas oil and at least 15% v/v of one or more components selected from aromatic hydrocarbons and oxygenates.
1. An additive composition for blending with fuel, the additive composition comprising at least 3% w/w of a viscosity index (VI) improving polymer; and a solvent mixture comprising in the range of from 10 to 85% v/v of a middle distillate gas oil and at least 15% v/v of at least one component selected from aromatic hydrocarbons and oxygenates.
2. The additive composition of claim 1 wherein the solvent mixture comprises an aromatic hydrocarbon component having a boiling point in the range of 170 to 370° C.
3. The additive composition of claim 1 wherein an aromatic hydrocarbon component is present in the solvent mixture in an amount of 15 to 60% v/v based on the total volume of the solvent mixture.
4. The additive composition of claim 3 wherein the aromatic hydrocarbon component is present in the solvent mixture in an amount of 25 to 50% v/v based on the total volume of the solvent mixture.
5. The additive composition of claim 4 wherein the aromatic hydrocarbon component is present in the solvent mixture in an amount of 30 to 40% v/v based on the total volume of the solvent mixture.
6. The additive composition of claim 1 wherein the solvent mixture comprises an oxygenate component selected from fatty acid alkyl esters.
7. The additive composition of claim 1 wherein an oxygenate component is present in the solvent mixture in an amount of 2 to 60% v/v based on the total volume of the solvent mixture.
8. The additive composition of claim 7 wherein the oxygenate component is present in the solvent mixture in an amount of 3 to 25% v/v based on the total volume of the solvent mixture.
9. The additive composition of claim 8 wherein the oxygenate component is present in the solvent mixture in an amount of 4 to 10% v/v based on the total volume of the solvent mixture.
10. The additive composition of claim 1 wherein an oxygenate component is present at a concentration less than or equal to a concentration threshold associated with the oxygenate component in a fuel composition to which the additive composition is or is to be added.
11. The additive composition of claim 1 wherein the VI improving polymer comprises a block copolymer including an aromatic monomer.
12. The additive composition of claim 11 wherein the VI improving polymer comprises a polystyrene-polyisoprene di-block copolymer.
13. The additive composition of claim 1 wherein the middle distillate gas oil has a VK40, as measured by ENO ISO 3104, in the range of from 1.0 to 3.0 mm 2 /s, and an aromatics content, as measured by IP391 or EN12916, in the range of from 15 to 30% m/m.
14. The additive composition of claim 1 comprising in the range of from 5 to 15% w/w of a VI improving copolymer, wherein the solvent mixture comprises
40 to 75% v/v middle distillate gas oil;
10 to 50% v/v aromatic hydrocarbons; and
3 to 10% v/v fatty acid alkyl esters,
based on the total volume of the solvent mixture.
15. The additive composition of claim 1 wherein the composition has a kinematic viscosity at 40° C. of less than 400 mm 2 /s.
16. A method of incorporating a VI improving polymer into a fuel composition, the method comprising: mixing at least 3% w/w of a VI improving polymer with a solvent mixture including in the range of from 10 to 85% v/v of a middle distillate gas oil and at least 15% v/v of one or more components selected from aromatic hydrocarbons and oxygenates to form an additive composition; and blending the additive composition with the fuel composition.
17. The method of claim 16 wherein the fuel composition and the additive composition each comprise a concentration of an oxygenate, with the concentration of the oxygenate in the additive being less than or equal to the concentration of the oxygenate in the fuel.
18. A fuel composition and additive composition package comprising: a fuel composition having a fuel component concentration or concentration threshold associated therewith; and an additive composition comprising: at least 3% w/w of a viscosity index (VI) improving polymer and a solvent mixture which comprises in a range of 10 to 85% v/v of a middle distillate gas oil and at least 15% v/v of one or more components selected from aromatic hydrocarbons and oxygenates and including a concentration of the fuel component, wherein the concentration of the fuel component in the additive composition is no greater than the concentration or concentration threshold associated with the fuel component in the fuel composition.
19. The additive composition of claim 14 wherein the VI improving copolymer comprises an aromatic monomer.