Abstract: The present invention provides a liquid fuel composition comprising:—a base fuel suitable for use in an internal combustion engine; and—one or more polyetheramines having formula (I): wherein R is an —NR12 group where R1 is independently selected from hydrogen and a C1-C6 hydrocarbyl group, n is an integer in the range of from 6 to 37, m is an integer in the range of from 12 to 74 and p is 0 or 1. The liquid fuel composition provides improved lubricity and improved fuel economy benefits.

Abstract: The present invention provides a method of improving the performance of the lubricant of an internal combustion engine, said method comprising fuelling an internal combustion engine containing the engine lubricant with a liquid fuel composition comprising:—a base fuel suitable for use in an internal combustion engine; and—one or more poly (hydroxycarboxylic acid) derivative having a terminal amine group having formula (III): [Y—CO[O-A-CO]n—Zp]m—X wherein Y is hydrogen or optionally substituted hydrocarbyl group, A is a divalent optionally substituted hydrocarbyl group, n is from 1 to 100, m is 1 or 2, Z is an optionally substituted divalent bridging group, p is from 0 to 10, and X is terminal amine group or a group carrying a terminal amine group, wherein the terminal amine group is selected from —NR12, wherein R1 is independently selected from hydrogen and a C1-C6 hydrocarbyl group.

Abstract: A fuel composition is provided containing (i) a base fuel, (ii) a Fischer-Tropsch derived gas oil and (iii) an oxygenate. The components (ii) and (iii) can be used in a tertiary fuel blend with a base fuel (i) for the purpose of achieving for the composition (a) a neutral or close to neutral effect on elastomeric components compared to that of the base fuel, and/or (b) a neutral or better emissions performance (in particular with respect to NOx and/or particulate emissions) compared to that of the base fuel, preferably in addition to a neutral or close to neutral density for the composition with respect to that of the base fuel.

Abstract: A fuel composition is provided containing (i) a base fuel, (ii) a Fischer-Tropsch derived gas oil and (iii) an oxygenate. The components (ii) and (iii) can be used in a tertiary fuel blend with a base fuel (i) for the purpose of achieving for the composition (a) a neutral or close to neutral effect on elastomeric components compared to that of the base fuel, and/or (b) a neutral or better emissions performance (in particular with respect to NOx and/or particulate emissions) compared to that of the base fuel, preferably in addition to a neutral or close to neutral density for the composition with respect to that of the base fuel.