The present invention relates to novel compositions that contain a base oil and certain substituted fullerenes effective to improve the cold flow properties of the base oil. Typically the substituted fullerenes have the general formula:C.sub.Fn (GR.sub.y).sub.xIn the formula C.sub.Fn is a fullerene or mixture of fullerenes, n is the number of carbon atoms in the fullerene, x is an integer from 1 up to the maximum number of sites on the fullerene molecule available for adding substituent groups, G is a linking group that may be absent or present, and when present is an oxygen, sulfur, nitrogen, phenol, aniline, Mannich base or diazocarboxylate-derived group, y is an integer determined by the identity of G and equals 1 when G is absent or when present and selected from the group consisting of oxygen, sulfur and diazocarboxylate-derived linking groups, and equals 1 or 2 when G is a phenol or aniline linking group, and equals 2 when G is a nitrogen linking group, and when y equals 1 R is a substituted or unsubstituted hydrocarbyl group and when y equals 2 at most one R may be hydrogen while the remainder are hydrocarbyl groups, and the R group may be the same or different, and wherein when x is greater than 1 the GR.sub.y may be the same or different and at most one R may be hydrogen. Preferred are substituted fullerenes that are alkylamino-substituted fullerenes. The compositions are useful as flow-improvers properties.