An additive mixture containing the components (A), (B) and optionally (C), wherein component (A) is at least one compound of the formula (I) wherein p is zero or 1; m and n are independently of one another an integer from zero to 3; and the radicals R are independently of one another C1-C8alkyl, C1-C8alkoxy, hydroxy, halogen, C1-C8alkylthio, C1-C8alkylsulfoxy or 2 radicals R form together with 2 adjacent carbon atoms of the unsaturated parent ring a 5- to 7-membered carbocyclic or heterocyclic ring; component (B) is at least one compound of the formula (II) wherein x and y are independently of one another an integer from 2 to 10; the radicals A1, A2 and A3 are independently of one another C1-C10alkyl, C5-C12cycloalkyl unsubstituted or substituted by 1 to 3 C1-C10alkyl; phenyl unsubstituted or substituted by 1 to 3 C1-C10alkyl; or C7-C12phenylalkyl, and the radicals A2 and A3 are additionally hydrogen; with the proviso that at least one of the radicals A1 and A2 is branched C3-C10alkyl, C5-C12cycloalkyl unsubstituted or substituted by 1 to 3 C1-C10alkyl; phenyl unsubstituted or substituted by 1 to 3 C1-C10alkyl; or C7-C12phenylalkyl; and component (C) is a lubricant or a mixture of lubricants.