27 C.F.R. § 21.55 — Formula No. 28-A.
§ 21.55 Formula No. 28–A. (a) Formula. To every 100 gallons of alcohol add: One gallon or any combination totaling 1 gallon of either gasoline, unleaded gasoline, heptane, or rubber hydrocarbon solvent. (b) Authorized uses. (1) As a fuel: 611. Automobile and supplementary fuels. 612. Airplane and supplementary fuels. 613. Rocket and jet fuels. 620. Proprietary heating fuels. 630. Other fuel uses. (2) Miscellaneous uses: 812. Product development and pilot plant uses (own use only).