Ethanol Shield Fuel Stabilizer 1 Gallon (128 oz) Prevents Corrosion - Gasoline Treatment that Protects Fuel System- Fuel Saver - Treats up to 1280 Gallons.

This. And this. Leading stabilizers formulated for E20 and other ethanol blends include STA-BIL 360, Lucas Oil Safeguard, and B3C Ethanol Shield. [1, 2, 3, 4, 5, 6]