In addition to fuels which are allowed by Sport and Tuner Categories, Unlimited Category may use any grade of gasoline, or federally-approved E85. Gasolines consist entirely of hydrocarbon compounds. Gasoline may contain antioxidants, metal deactivators, corrosion inhibitors, and lead alkyl compounds such as tetraethyl lead. Oxygen and/or nitrogen bearing additives are prohibited except for those originally present in fuel which is federally approved for use on public highways. Oxygen and/or nitrogen bearing oil additives are prohibited in two-cycle engine oiling systems.