the additive into the fuel return line 16 such that the additive reaches the fuel tank 10 and can be conveyed to the diesel engine 13 together with the fuel via the fuel supply line 15 a module 12 with a filling level sensor and or filling level display can be provided for the filling level of the fuel tank an additive that facilitates the regeneration of the diesel particulate filter is advantageously used this may be a catalytic solution for example i e metal based in particular containing iron iron compounds such as fe2o3 platinum or other metal catalysts fig2 provides an example of a load characteristic map for the diesel particulate filter the exhaust gas volume flow in m 3 h is plotted on the x axis and the exhaust gas backpressure in mbar on the y axis curves are shown for the exhaust gas backpressure as a function of the exhaust gas volume flow the first curve 110 shows the condition for no load 0 g m 2 the second curve 120 for a load here e g 24 g m 2 starting at which a regeneration can be conducted meaningfully and the third curve 130 for a load here e g 36 g m 2 starting at which regeneration should no longer be conducted in order to keep from endangering the diesel particulate filter from too high a temperature during regeneration characteristic maps for the relationship between the exhaust gas temperature air flow and differential pressure in the three load states of a no load b lower threshold for regeneration and c upper threshold for regeneration are stored for a diesel particulate filter as a function of its geometry and size no information about the internal combustion engine is required for these.