Disclosed herein is an apparatus and method for adding a lubricating additive to a diesel fuel. In one exemplary embodiment a diesel fuel filter is provided, the diesel fuel filter comprising: a housing having at least one inlet opening and at least one outlet opening configured to define a flow path therethrough; filter media disposed in the flow path; and an additive cartridge configured to disperse a lubricating additive into diesel fuel passing through the filter, wherein the fuel filter comprises an adsorbent comprising an inorganic oxide having a surface acidity characterized by a pKa of less than or equal to −3.