The invention relates to low-temperature-stabilized fatty acid mixtures comprising A) from 10 to 99.99% by weight of fatty acid mixtures comprising: A1) from 1 to 99% by weight of at least one saturated mono- or dicarboxylic acid having 6 to 50 carbon atoms, A2) from 1 to 99% by weight of at least one unsaturated mono- or dicarboxylic acid having 6 to 50 carbon atoms, and B) from 0.01 to 90% by weight of copolymers comprising: B1) from 40 to 60 mol % of bivalent structural units of the formula ##STR1## where X.dbd.O or N--R.sup.1, in which a and b=0 or 1 and a+b=1, and B2) from 60 to 40 mol % of bivalent structural units of the formula --H.sub.2 C--CR.sup.2 R.sup.3 -- B2 and, if desired, B3) from 0 to 20 mol % of bivalent structural units derived from polyolefins, where the polyolefins can be derived from monoolefins having 3 to 5 carbon atoms, and in which a) R.sup.1 is an alkyl or alkenyl radical having from 10 to 40 carbon atoms or an alkoxyalkyl radical having from 1 to 100 alkoxy units and from 1 to 30 carbon atoms in the alkyl radical, and b) R.sup.3 is a radical of the formula OCOR.sup.4 or COOR.sup.4, in which R.sup.4 is C.sub.1 -C.sub.24 -alkyl, and c) the number of carbon atoms in the polyolefin molecules on which the structural units B3) are based is from 35 to 350, and d) R.sup.2 is hydrogen or methyl, and to the use of these mixtures for improving the lubrication properties of low-sulfur middle distillates.