NOVELTY - Reducing the amount of oxidative metals pick-up in a fuel composition involves: adding to the fuel composition an additive comprising a hydrocarbon substituted with at least two carboxy functionalities in the form of acids or at least one carboxy functionality in the form an anhydride.    USE - For reducing the amount of oxidative metals pick-up in a fuel composition selected from diesel fuel and/or biodiesel, during the operation of an internal combustion engine, where the oxidative metal, for which pick-up is being reduced, is selected from copper, zinc, and/or iron (claimed), vanadium, chromium, cobalt, nickel, and manganese. The method is particularly useful for a liquid fuel and/or for the operation of an internal combustion engine, including either compression ignition engines or spark ignited engines. The internal combustion engine includes 2-stroke or 4-stroke engines fuelled with gasoline, diesel, a natural gas, or a mixed gasoline/alcohol. The compression ignition engines include both light duty and heavy duty diesel engines. The spark ignited engines include port and direct injection gasoline engines.    ADVANTAGE - The method results in the reduction of injector deposits in an engine in which the fuel composition is applied; and the fuel is susceptible to pick up of oxidative metals to a level greater than 0.5 parts per million (ppm) when left in contact for an extended period of time with solid materials containing the metal. The fuel composition effectively reduces the amount of metal pick-up, and more specifically, zinc pick-up while minimizes the impact on additive and fuel composition costs and complexity. The additive compositions provide comparable and/or improved detergency, specifically improved engine deposit control when they are used in fuel compositions. These characteristics allow for improved engine performance, including reductions in injector fouling, reduced deposit-caused engine power losses, reduced deposit-caused fuel economy losses and reduced deposit-caused engine emissions. The method provides a reduction in metal pick-up of at least 5%, preferably at least 20% and especially at least 50%; and the method ensures a metal level of a fuel composition that does not rise above 10 ppm, preferably 5 ppm, especially 1 ppm and particularly 0.1 ppm of metal content.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) a fuel composition comprising a fuel; an additive comprising a hydrocarbon substituted with at least two carboxy functionalities in the form of acids or at least one carboxy functionality in the form an anhydride; and optional additional performance additives; and    (2) a fuel additive composition comprising: an optional solvent; an additive comprising a hydrocarbon substituted with at least two carboxy functionalities in the form of acids or at least one carboxy functionality in the form an anhydride; and optional additional performance additives.