A fuel composition for a spark-ignition internal combustion engine comprises a non-metallic octane-boosting additive. The non-metallic octane-boosting additive is an additive which, when used at a treat rate of 0.67 % by weight, increases the research octane number of a fuel by at least 1.8 whilst maintaining the T.sub.90 and/or the vapour pressure.

A fuel composition for a spark-ignition internal combustion engine comprises a non-metallic octane-boosting additive. The non-metallic octane-boosting additive is an additive which, when used at a treat rate of 0.67 % by weight, increases the research octane number of a fuel by at least 1.8 whilst maintaining the T.sub.90 and/or the vapour pressure.

A method for improving the ferrous corrosion-preventing characteristics of a fuel comprises combining an additive having a chemical structure comprising a 6-membered aromatic ring sharing two adjacent aromatic carbon atoms with a 6- or 7-membered saturated heterocyclic ring, the 6- or 7-membered saturated heterocyclic ring comprising a nitrogen atom directly bonded to one of the shared carbon atoms to form a secondary amine and an atom selected from oxygen or nitrogen directly bonded to the other shared carbon atom, the remaining atoms in the 6- or 7-membered heterocyclic ring being carbon with the fuel. The additive may also be used for preventing ferrous corrosion in a system which comprises a fuel, such as a fuel system in a vehicle.

A method for improving the ferrous corrosion-preventing characteristics of a fuel comprises combining an additive having a chemical structure comprising a 6-membered aromatic ring sharing two adjacent aromatic carbon atoms with a 6- or 7-membered saturated heterocyclic ring, the 6- or 7-membered saturated heterocyclic ring comprising a nitrogen atom directly bonded to one of the shared carbon atoms to form a secondary amine and an atom selected from oxygen or nitrogen directly bonded to the other shared carbon atom, the remaining atoms in the 6- or 7-membered heterocyclic ring being carbon with the fuel. The additive may also be used for preventing ferrous corrosion in a system which comprises a fuel, such as a fuel system in a vehicle.

Use of a hydrocarbyl-substituted dicarboxylic acid for improving or boosting the separation of water from fuel oils and gasoline fuels which comprise additives with detergent action. A Fuel additive concentrate comprising the said hydrocarbyl-substituted dicarboxylic acid, certain additives with detergent action and optionally other customary additives and solvents or diluents.

A gasoline additive composition includes an oxygenate gasoline additive; and an optical brightener. The gasoline additive composition can be used in a gasoline blend.

Disclosed herein are beta-amino ester surfactant compounds and compositions useful in applications relating to inhibition of gas hydrate agglomerates in the production, transportation, storage, and separation of crude oil and natural gas. Also disclosed herein are methods of using the compounds and compositions as gas hydrate inhibitors, particularly in applications relating to the production, transportation, storage, and separation of crude oil and natural gas.

Disclosed herein are beta-amino ester surfactant compounds and compositions useful in applications relating to inhibition of gas hydrate agglomerates in the production, transportation, storage, and separation of crude oil and natural gas. Also disclosed herein are methods of using the compounds and compositions as gas hydrate inhibitors, particularly in applications relating to the production, transportation, storage, and separation of crude oil and natural gas.

Quaternary ammonium salts of formula: wherein each of R.sup.1 and R.sup.2 is independently selected from an optionally substituted alkyl, alkenyl or aryl group having less than 8 carbon atoms, R together with N forms an aliphatic or aromatic heterocycle having less than 12 carbons atoms and R.sup.5 is hydrogen or an optionally substituted hydrocarhyl group. The use of these compounds as fuel or lubricant additives, especially as diesel fuel additives,

The use of tetrahydrobenzoxazines I

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where R.sup.1 is a hydrocarbyl radical and R.sup.2, R.sup.3, R.sup.4 and R.sup.5 are each independently hydrogen atoms, hydroxyl groups or hydrocarbyl radicals, and where R.sup.2 to R.sup.5 may also form a second and a third tetrahydrooxazine ring, with the proviso that at least one of the substituents has from 4 to 3000 carbon atoms and the remaining substituents, when they are hydrocarbyl radicals, each have from 1 to 20 carbon atoms, as stabilizers for stabilizing inanimate organic material, especially turbine fuels, against the action of light, oxygen and heat.