Copolymers comprising C.sub.14 to C.sub.50 olefins and at least two different olefindicarboxylic esters and optionally maleic acid or maleic acid derivatives. The olefindicarboxylic esters are firstly esters with linear C.sub.18- to C.sub.50-alkyl groups and secondly esters with short-chain linear, branched or cyclic alkyl groups, or esters with aromatic groups. The invention further relates to a process for preparing copolymers of this kind and to the use thereof as pour point depressant for crude oil, mineral oil and/or mineral oil products, preferably as pour point depressant for crude oil.

Copolymers comprising C.sub.14 to C.sub.50 olefins and at least two different olefindicarboxylic esters and optionally maleic acid or maleic acid derivatives. The olefindicarboxylic esters are firstly esters with linear C.sub.18- to C.sub.50-alkyl groups and secondly esters with short-chain linear, branched or cyclic alkyl groups, or esters with aromatic groups. The invention further relates to a process for preparing copolymers of this kind and to the use thereof as pour point depressant for crude oil, mineral oil and/or mineral oil products, preferably as pour point depressant for crude oil.

The invention relates to quaternary ammonium amide and/or ester salts and their use as additives, including their use in fuels, such as diesel fuel. The invention particularly relates to the use of quaternary ammonium amide and/or ester salts as detergents in diesel fuels.

The invention relates to quaternary ammonium amide and/or ester salts and their use as additives, including their use in fuels, such as diesel fuel. The invention particularly relates to the use of quaternary ammonium amide and/or ester salts as detergents in diesel fuels.

An additive composition, on use in a fuel in a spark-ignition internal combustion engine, controls the formation of sludge and piston varnish. When used in a direct injection spark-ignition internal combustion engine, particulate emissions and deposit formation on intake valves may also be controlled. When used in a port fuel injection spark-ignition internal combustion engine, the port fuel injection valve deposits may be reduced. The additive composition comprises a polyalkylene amine and a hydrocarbyl-substituted hydroxyaromatic compound. The additive compositions may be present in a fuel composition.

An additive composition, on use in a fuel in a spark-ignition internal combustion engine, controls the formation of sludge and piston varnish. When used in a direct injection spark-ignition internal combustion engine, particulate emissions and deposit formation on intake valves may also be controlled. When used in a port fuel injection spark-ignition internal combustion engine, the port fuel injection valve deposits may be reduced. The additive composition comprises a polyalkylene amine and a hydrocarbyl-substituted hydroxyaromatic compound. The additive compositions may be present in a fuel composition.

The use as a sludge controlling additive in a fuel composition for a spark-ignition internal combustion engine or a compression-ignition gasoline internal combustion engine of a combination of: a. a hydrocarbyl-substituted aromatic compound; and b. a polyalkylene amine. The fuel composition may also be used for maintaining oil pathways and/or lubrication in an engine.

The use as a sludge controlling additive in a fuel composition for a spark-ignition internal combustion engine or a compression-ignition gasoline internal combustion engine of a combination of: a. a hydrocarbyl-substituted aromatic compound; and b. a polyalkylene amine. The fuel composition may also be used for maintaining oil pathways and/or lubrication in an engine.

An enhanced fuel, a method of producing such enhanced fuel, and method of using such enhanced fuel for operating internal combustion engine. The fuel includes a mixture of at least one alcohol, water and ammonium nitrate (AN) as a cetane enhancer. The water is included in a quantity which renders the ammonium nitrate dissolved in the at least one alcohol. The fuel further contains dimethylether as an ignition-improver additive, at least one lubricity agent and at least one anti-corrosion agent.

An enhanced fuel, a method of producing such enhanced fuel, and method of using such enhanced fuel for operating internal combustion engine. The fuel includes a mixture of at least one alcohol, water and ammonium nitrate (AN) as a cetane enhancer. The water is included in a quantity which renders the ammonium nitrate dissolved in the at least one alcohol. The fuel further contains dimethylether as an ignition-improver additive, at least one lubricity agent and at least one anti-corrosion agent.