NOVELTY - Fuel- or lubricant composition comprises at least one reaction product comprising a quaternized nitrogen compound, or its partial fraction, which contains the quaternized nitrogen compound, and is obtained from the reaction product by purification, in a fuel or a lubricant. The reaction product is obtainable by reacting a quaternizable alkylamine containing at least one quaternizable tertiary amino group, with a quaternizing agent comprising e.g. an aliphatic polycarboxylic acid, preferably a dicarboxylic acid, which converts the tertiary amino group into a quaternary ammonium group.    USE - The fuel- or lubricant composition is useful as diesel fuels, biodiesel fuels, gasoline fuels or alkanol-containing gasoline fuels. The quaternized nitrogen compound is useful as a fuel- or lubricant additive, preferably as an additive for reducing fuel consumption and for minimizing power loss in direct injection diesel engines, preferably diesel engines with common-rail injection systems, as a gasoline fuel additive for reducing deposits in intake system of a gasoline engine, preferably direct-injection-spark-ignition- and port fuel injector engines, as a diesel fuel additive for reducing and/or preventing deposits in fuel injection systems, preferably internal diesel injector deposits and for reducing and/or preventing valve sticking in direct-injection diesel engines, preferably common-rail injection systems (all claimed).    DETAILED DESCRIPTION - Fuel- or lubricant composition comprises at least one reaction product comprising a quaternized nitrogen compound, or its partial fraction, which contains the quaternized nitrogen compound, and is obtained from the reaction product by purification, in a fuel or a lubricant. The reaction product is obtainable by reacting a quaternizable alkylamine containing at least one quaternizable tertiary amino group, with a quaternizing agent comprising (a) an alkyl ester of a cyclo-aromatic or cycloaliphatic mono- or polycarboxylic acid, preferably a mono- or dicarboxylic acid, (b) an aliphatic polycarboxylic acid, preferably a dicarboxylic acid, (c) a hydrocarbyl epoxide optionally in combination with a free acid, or (d) a dialkyl carbonate, which converts the tertiary amino group into a quaternary ammonium group. INDEPENDENT CLAIMS are also included for:    (1) the quaternized nitrogen compound;    (2) preparing the quaternized nitrogen compound, comprising reacting the quaternizable alkylamine with the quaternizing agent including (a)-(c); and    (3) an additive concentrate comprising the quaternized nitrogen compound in combination with further diesel or gasoline fuel additives or lubricant additives.