E10

E10: Every vehicle's ethanol blend.

E10 is 10% ethanol and 90% unleaded gasoline. Today, this fuel blend is covered under warranty by every U.S. automobile manufacturer, for every make and every model, and is recommended by many because of its high octane and superior performance characteristics.

E10 is the blend in the majority of the more than 4.8 billion gallons of ethanol used annually in the U.S. Blends of 5.7% or 7.7% are used in a few areas of the country. 

Ethanol has been around for centuries. In its most basic form, ethanol is grain alcohol. Henry Ford envisioned his autos running on this form of alcohol instead of gasoline.

Buying ethanol.

As ethanol-enriched fuel becomes more common, it is becoming available at more pumps. Ethanol blends are sold throughout the country.

Each state determines its pump labeling laws - everything from mandatory to voluntary. Look for pumps labeled with the amount of ethanol contained in the fuel, and branded with the "e" brand.

Octane and oxygenate.

Pure ethanol has an octane rating of 113. Adding 10% ethanol to unleaded gasoline will raise the fuel's octane rating by 2 or 3 points.

Ethanol is an oxygenate, which means it adds valuable oxygen to the gasoline. With more oxygen in the fuel, it burns more completely and cleanly. Ethanol is 35% oxygen by weight; a 10% ethanol blend produces gasoline with 3.5% oxygen. Some areas of the U.S. with air pollution concerns require oxygenates.