The invention relates to an additive mixture for fuels, which comprises a) at least one N-formal, b) at least one antioxidant and c) at least one corrosion inhibitor. The additive mixture ensures that the additized fuels and lubricants have biocidal and corrosion-inhibiting additization, especially when they comprise proportions of renewable raw materials, such as biodiesel, and when they are in contact with copper-containing surfaces.