Fuel compositions comprising at least 10 ppm by weight of a succinic ester acid amine salt or a succinamide acid amine salt (both amine salt(s)). The amine salt is the product of (a) and (b), wherein: (a) is an amine with (i) at least one tertiary nitrogen and (ii) at least one hydroxy alkyl functional group and/or at least one secondary amine functionality; and (b) is a hydrocarbyl-substituted succinic acid/or anhydride. The molar ratio of (a) to (b) may range from 3:1 to 1:3. The fuel composition may comprise gasoline, oxygenate, or mixtures thereof. Methods and uses for reducing carbonaceous deposits in an engine comprising operating the engine using the fuel composition having an amine salt therein.

Provided is a method of dispersing asphaltenes to inhibit asphaltene precipitation and/or deposition in a hydrocarbon. The method includes adding to the hydrocarbon an asphaltene dispersing agent which is an ester of a mono-carboxylic fatty acid and a sugar. The sugar has at least 4 hydroxyl groups. In addition, more than one of the hydroxyl groups on the sugar are reacted with the mono-carboxylic fatty acid to form the ester.

A quaternary ammonium compound of formula (I): (I) wherein R.sup.0, R.sup.1, R.sup.2 and R.sup.3 is each independently an optionally substituted hydrocarbyl group, X is a linking group, R.sup.4 is an optionally substituted alkylene group, R5 is hydrogen or an optionally substituted alkyl, alkenyl or aryl group, and n is 0 or a positive integer, provided that n is not 0 when R5 is hydrogen.

##STR00001##

A diesel fuel composition comprising as an additive an ester compound which is the reaction product of a polyhydric alcohol of formula H(OR).sub.nOH and at least 1.5 molar equivalents of an optionally substituted polycarboxylic acid or an anhydride thereof, wherein R is an optionally substituted alkylene group and n is at least 1.

A diesel fuel composition comprising as an additive an ester compound which is the reaction product of an optionally substituted polycarboxylic acid or an anhydride thereof and an alcohol or formula ROH, wherein R is an optionally substituted hydrocarbyl group.

A composition containing diesel (e.g., containing less than about 15 ppm sulfur) and fatty acid methyl ester/maleic anhydride/esters (FAME/MA/esters), wherein the FAME/MA/esters are prepared by a method involving reacting FAME with MA to form FAME/MA and reacting FAME/MA with alkyl alcohol to form FAME/MA/esters; wherein the FAME is conjugated. The FAME/MA/esters are produced from tung oil or from plant oils in which the unsaturated fatty acids have been converted to conjugated fatty acids. Also a method of improving the lubricity of diesel, involving combining diesel and FAME/MA/esters, wherein the FAME/MA/esters are prepared by a method involving reacting FAME with MA to form FAME/MA and reacting FAME/MA with alkyl alcohol to form FAME/MA/esters; wherein the FAME is conjugated.

A quaternary ammonium salt of formula (I): (I) where in X is a linking group; Y is O, NH or NR.sup.1 wherein R.sup.1is H or an optionally substituted hydrocarbyl group; Q.sup. is a moiety that includes a quaternary ammoniumcation; A.sup. is an anion; R.sup.2 is an optionally substituted alkylene group; R.sup.3 is hydrogen or an optionally substituted hydrocarbyl group; and n is 0 or a positive integer; provided that n is not 0 when R.sup.3 is hydrogen.

##STR00001##

A diesel fuel composition comprising as an additive an ester compound which is the reaction product of an optionally substituted polycarboxylic acid or an anhydride thereof and a compound or formula H(OR).sub.nOR.sup.1, wherein R is an optionally substituted alkylene group, R.sup.1 is an optionally substituted hydrocarbyl group and n is at least 1.

Additive compositions comprising (a) a hydroxycarboxylic acid; and (b) a compound derived from a hydrocarbyl-substituted succinic acid or anhydride wherein the ratio of (a) to (b) in the additive composition ranges from 1:9 to 9:1. The additive compositions may be added to a fuel. Methods of reducing wear in an engine comprising operating the engine using a fuel composition have the additive composition therein. The use of an additive composition in a fuel composition to reduce the fuel composition's coefficient of friction or to reduce wear in an engine.

The testing of various chemicals has yielded new chemicals and chemical mixtures for the use of removing carbon deposits from the internal combustion engine. Some of these chemicals and chemical mixtures have proven to work better across many different carbon types than other chemicals that were tested. These chemical terpenes are typically produced from plants. One standard terpene mixture is known as turpentine. The chemical turpentine and chemicals found in turpentine have been determined, through our research and testing, to be extremely effective at removing the carbon that is produced within the internal combustion engine.