The present invention relates to the use, for reducing deposits in the internal parts of a spark ignition engine, of a fuel composition comprising at least three additives: a quaternary ammonium salt, a non-quaternary polyisobutylene succinimide and a Mannich base which is different from the other additives. The composition is such that the mass ratio of the quantity of the first additive to the quantity of the second additive is in the range from 0.2:1 to 2.5:1.

Amines and amine derivatives that improve the buffering range, and/or reduce the chelation and other negative interactions of the buffer and the system to be buffered. The reaction of amines or polyamines with various molecules to form polyamines with differing pKa's will extend the buffering range, derivatives that result in polyamines that have the same pKa yields a greater buffering capacity. Derivatives that result in zwitterionic buffers improve yield by allowing a greater range of stability.

Amines and amine derivatives that improve the buffering range, and/or reduce the chelation and other negative interactions of the buffer and the system to be buffered. The reaction of amines or polyamines with various molecules to form polyamines with differing pKa's will extend the buffering range, derivatives that result in polyamines that have the same pKa yields a greater buffering capacity. Derivatives that result in zwitterionic buffers improve yield by allowing a greater range of stability.

A fuel composition comprising as an additive the reaction product of a polycarboxylic acid compound of formula (I): (I) or an anhydride thereof; and an alcohol having at least 5 carbon atoms; wherein each of n and m may be 0 or a positive integer.

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A fuel composition comprising as an additive the reaction product of a polycarboxylic acid having no more than 5 carbon atoms per carboxylic acid group, or an anhydride thereof and an alcohol having at least 5 carbon atoms.

Method for reducing intake valve deposits in a spark ignition internal combustion engine which is fuelled with a gasoline fuel composition, wherein the method comprises introducing into the engine an aqueous based composition, wherein the aqueous based composition comprises (i) water, (ii) from 0 vol % to 40 vol % freezing point suppression agent, (iii) from 0 vol % to 10 vol % of surfactant, and (iv) an amine compound in a blending amount of from 0 ppmw to 1000 ppmw.

Method for reducing intake valve deposits in a spark ignition internal combustion engine which is fuelled with a gasoline fuel composition, wherein the method comprises introducing into the engine an aqueous based composition, wherein the aqueous based composition comprises (i) water, (ii) from 0 vol % to 40 vol % freezing point suppression agent, (iii) from 0 vol % to 10 vol % of surfactant, and (iv) an amine compound in a blending amount of from 0 ppmw to 1000 ppmw.

A composition comprising at least one fuel that is a diesel fuel, a biodiesel fuel, or combinations thereof and less than 100 ppm, less than 50 ppm (or less than 25 ppm, less than 10 ppm, 1 to 7 ppm, or 5 to 7 ppm) of an alkylene-coupled C.sub.10 to C.sub.60 (or C.sub.10 to C.sub.40, C.sub.14 to C.sub.32 or C.sub.24 to C.sub.28) alkylphenol; 25 to 500 ppm (or 50 to 500 ppm, or 150 to 450 ppm or 250 to 450 ppm, or 250 to 400 ppm) of a terpolymer; and 5 to 90 ppm, (or 10 to 70 ppm, to 60 ppm, or 10 to 55 ppm) of hydrocarbyl-substituted amine detergent having at least one tertiary amino group.

Methods of reducing the cold filter plugging point (“CFPP”) of a fuel, said method comprising adding the following components: less than 100 ppm, less than 50 ppm (or less than 25 ppm; less than 10 ppm, 1 to 7 ppm, or 5 to 7 ppm) of an alkylene-coupled C.sub.10 to C.sub.60 (or C.sub.10 to C.sub.40, C.sub.14 to C.sub.32 or C.sub.24 to C.sub.28) alkylphenol; 25 to 500 ppm (or 50 to 500 ppm, or 150 to 450 ppm or 250 to 450 ppm, or 250 to 400 ppm) of a terpolymer; and 5 to 90 ppm, (or 10 to 70 ppm, to 60 ppm, or 10 to 55 ppm) of hydrocarbyl-substituted amine detergent having at least one tertiary amino group.

Uses of a fuel additive composition to reduce the cold filter plugging point (“CFPP”) of a fuel, wherein the fuel additive composition comprises: 0.2 to 3 wt % of an alkylene-coupled C.sub.10 to C.sub.60 (or C.sub.10 to C.sub.40, C.sub.14 to C.sub.32 or C.sub.24 to C.sub.28) alkylphenol; 10 to 50 wt % of a terpolymer; and 2 to 10 wt % of hydrocarbyl-substituted amine detergent having at least one tertiary amino group; and an optional solvent.

A composition comprising at least one fuel that is a diesel fuel, a biodiesel fuel, or combinations thereof and less than 100 ppm, less than 50 ppm (or less than 25 ppm, less than 10 ppm, 1 to 7 ppm, or 5 to 7 ppm) of an alkylene-coupled C.sub.10 to C.sub.60 (or C.sub.10 to C.sub.40, C.sub.14 to C.sub.32 or C.sub.24 to C.sub.28) alkylphenol; 25 to 500 ppm (or 50 to 500 ppm, or 150 to 450 ppm or 250 to 450 ppm, or 250 to 400 ppm) of a terpolymer; and 5 to 90 ppm, (or 10 to 70 ppm, to 60 ppm, or 10 to 55 ppm) of hydrocarbyl-substituted amine detergent having at least one tertiary amino group.

Methods of reducing the cold filter plugging point (“CFPP”) of a fuel, said method comprising adding the following components: less than 100 ppm, less than 50 ppm (or less than 25 ppm; less than 10 ppm, 1 to 7 ppm, or 5 to 7 ppm) of an alkylene-coupled C.sub.10 to C.sub.60 (or C.sub.10 to C.sub.40, C.sub.14 to C.sub.32 or C.sub.24 to C.sub.28) alkylphenol; 25 to 500 ppm (or 50 to 500 ppm, or 150 to 450 ppm or 250 to 450 ppm, or 250 to 400 ppm) of a terpolymer; and 5 to 90 ppm, (or 10 to 70 ppm, to 60 ppm, or 10 to 55 ppm) of hydrocarbyl-substituted amine detergent having at least one tertiary amino group.

Uses of a fuel additive composition to reduce the cold filter plugging point (“CFPP”) of a fuel, wherein the fuel additive composition comprises: 0.2 to 3 wt % of an alkylene-coupled C.sub.10 to C.sub.60 (or C.sub.10 to C.sub.40, C.sub.14 to C.sub.32 or C.sub.24 to C.sub.28) alkylphenol; 10 to 50 wt % of a terpolymer; and 2 to 10 wt % of hydrocarbyl-substituted amine detergent having at least one tertiary amino group; and an optional solvent.

Lubricity additives for hydrocarbon fuels are presented according to formula I:

R.sup.1[(—O—R.sup.2).sub.n-Q].sub.p  (I)

wherein p is 3 or greater; each n is independently selected from integers equal to 2 or greater; R.sup.1 is a C3-C20 aliphatic hydrocarbon group of valence p which is branched or linear and which is substituted or unsubstituted; each R.sup.2 is independently selected from C2-C20 divalent aliphatic or aromatic hydrocarbon groups which are branched or linear and which are substituted or unsubstituted; and each Q is independently selected from —NH.sub.2 or a moiety according to formula II:

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wherein each R.sup.3 is independently selected from C8-C60 alkenyl groups which are substituted or unsubstituted, providing that at least one Q is the moiety according to formula II.