NOVELTY - Additive composition comprises modified alkylphenol-aldehyde resin obtained by Mannich reaction of alkylphenol-aldehyde condensation resin with aldehyde and/or ketone having 1-8, preferably 1-4 carbon atoms and hydrocarbon compound having alkyl monoamine or alkylpolyamine (alkylamine) group having 4-30 carbon atoms, and filterability additives consisting of homopolymers of 1-40C-alkyl (meth)acrylate, preferably 8-24C-alkyl polyacrylate, terpolymers of 4-22C-alkyl (meth)acrylate, 20-24C- alpha -olefin and maleimide, and ammonium salts of mono or polycarboxylic acid.    USE - The additive composition is useful in fuels or hydrocarbon liquid fuels for improving their cold properties and for decreasing the filterability temperature measured according to standard NF EN 116 and dispersion of paraffins and/or limiting the sedimentation of paraffins in fuel or a hydrocarbon liquid fuel, where the fuel or hydrocarbon liquid fuel is jet fuels, gas oils, diesel fuels, domestic fuel and heavy fuel oil (all claimed).    ADVANTAGE - The additive composition can improve cold properties of fuels or hydrocarbon liquid fuels without affecting the effectiveness of the modified alkylphenol-aldehyde resin on the dispersion and/or sedimentation of paraffins.    DETAILED DESCRIPTION - Additive composition comprises at least one modified alkylphenol-aldehyde resin, and at least first and second filterability additives. The modified alkylphenol-aldehyde resin is obtained by Mannich reaction of alkylphenol-aldehyde condensation resin with at least one aldehyde and/or ketone having 1-8 carbon atoms, preferably 1-4 carbon atoms and at least one hydrocarbon compound having at least one alkyl monoamine or alkylpolyamine (alkylamine) group having 4-30 carbon atoms. The alkylphenol-aldehyde condensation resin is obtained by condensation of at least one alkylphenol substituted by at least one linear or branched 1-30C-alkyl, preferably monoalkylphenol with at least one aldehyde and/or ketone having 1-8 carbon atoms, preferably 1-4 carbon atoms. The first filterability additive consists of homopolymers of 1-40C-alkyl (meth)acrylate, preferably 8-24C-alkyl polyacrylate. The second filterability additive consists of terpolymers of 4-22C-alkyl (meth)acrylate, 20-24C- alpha -olefin and maleimide N-substituted by 4-30C-hydrocarbon chain, and ammonium salts of mono or polycarboxylic acid comprising at least one linear or branched, optionally saturated 4-30C-hydrocarbon chain. An INDEPENDENT CLAIM is included for fuels or liquid hydrocarbon fuels composition whose boiling temperature of 100-500 degrees C comprising a major proportion of hydrocarbon compound and/or vegetable and/or animal oils and/or their esters of oils and/or animal and/or vegetable biodiesel, and a minor proportion of, preferably 5-500 ppm of at least the additive composition.