The present invention relates to additive compositions that improve the stability and the engine performances of diesel fuels, in particular diesel fuels of the off-road type in accordance with the decree of 10 December 2010. The compositions have, in particular, improved properties, especially relative to the oxidation resistance, the storage stability, the thermal stability, the reduction in the fouling of the injectors, the reduction in the loss of power, and the tendency of the filters to clog up. The additive compositions comprise: a) at least one metal deactivator or chelating agent, b) at least one antioxidant of hindered phenol (alkylphenol) type, c) at least one dispersant and/or a detergent, and d) at least one metal passivator.