27 CFR § 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).