Substituted fullerenes as flow improvers

An additive concentrate, comprising a mixture of a flow improving amount of a substituted fullerene in a liquid medium compatible with a fuel, wherein the substituted fullerenes represented by the formula:

• C.sub.Fn (GRy)x
• wherein C.sub.Fn is a fullerene or mixture of fullerenes, n is the number of carbons in the fullerene, wherein G is a linking group between the fullerene and R that may be absent or when present is selected from the group consisting of oxygen, sulfur, nitrogen, phenol, aniline, Mannich base and diazocarboxylate-derived groups, wherein R is a hydrocarbyl group, y is a positive integer determined by the identity of G, and y equals 1 when G is absent or when G is present and selected from the group consisting of oxygen, sulfur, and diazocarboxylate-derived linking groups, and y equals 1 or 2 when G is selected from the group consisting of phenol and aniline linking groups, and y equals 2 when G is a nitrogen linking group, and wherein when y equals 1 R is a hydrocarbyl group and when y equals 2, one R group is selected from a hydrocarbyl group and H and the remaining R is a hydrocarbyl group, and the R groups may be the same or different, wherein x is an integer from 1 up to the maximum number of sites on the fullerene available for adding substituent groups, and wherein when x is greater than 1 the GRy may be the same or different from each other.

A flow improving amount of a substituted fullerene in combination with at least one fuel additive, whereto the substituted fullerene is represented by the formula:

• C.sub.Fn (GRy)x
• wherein CFn is a fullerene or mixture of fullerenes, n is the number of carbons in the fullerene, wherein G is a linking group between the fullerene and R that may be absent or when present is selected from the group consisting of oxygen, sulfur, nitrogen, phenol, aniline, Mannich base and diazocarboxylate-derived groups, wherein R is a hydrocarbyl group, y is a positive integer determined by the identity of G, and y equals 1 when G is absent or when G is present and selected from the group consisting of oxygen, sulfur, and diazocarboxylate-derived linking groups, and y equals 1 or 2 when G is selected from the group consisting of phenol and aniline linking groups, and y equals 2 when G is a nitrogen linking group, and wherein when y equals 1 R is a hydrocarbyl group and when y equals 2, one R group is selected from a hydrocarbyl group and H and the remaining R is a hydrocarbyl group, and the R groups may be the same or different, wherein x is an integer from 1 up to the maximum number of sites on the fullerene available for adding substituent groups, and wherein when x is greater than 1 the GRy may be the same or different from each other.