E10 vs E15 vs E85: U.S. ethanol fuels explained
Compare the three ethanol blends sold in the U.S.: ethanol content, which vehicles can use each, octane and how to read the pump labels.
Updated 25 October 2026
At a glance
| E10 | E15 | E85 (flex fuel) | |
|---|---|---|---|
| Ethanol | Up to 10% | 10.5–15% | 51–83% |
| Who can use it | Any gasoline vehicle or engine | Cars and light trucks from MY 2001, flex-fuel vehicles | Flex-fuel vehicles only |
| Not for | Check old classics and small-engine manuals | Pre-2001 cars, motorcycles, boats, off-road and heavy-duty engines | Any vehicle that is not flex-fuel |
| At the pump | Regular unleaded | Often "Unleaded 88", orange label | Yellow nozzle or cap on many FFVs |
Is my car a flex-fuel vehicle?
Look for a yellow fuel cap or a yellow ring in the filler neck, an "FFV", "E85" or "Flex Fuel" badge, or check your owner's manual. The U.S. Department of Energy also publishes a flex-fuel vehicle search.
E10 is the safe default
E10 is allowed in essentially every gasoline engine, which is why it is the regular grade nationwide. If you're not sure your vehicle or equipment can take E15 or E85, use E10.
Is your vehicle approved?
See the U.S. rules for E10, E15 and E85.
Frequently asked questions
Can I put E85 in a normal car?
No. Only flex-fuel vehicles are designed for E85. In a normal car it can cause running problems and damage.
Why is E85 cheaper?
Ethanol is often cheaper per gallon, but it contains less energy, so FFVs get fewer miles per gallon on E85.
Sources
- U.S. Department of Energy (AFDC) – E15 (checked 25 October 2026)
- U.S. Department of Energy (AFDC) – Flexible fuel vehicles (checked 25 October 2026)
Related guides
- What is E10 petrol? A plain-English guide
- E10 in lawnmowers, chainsaws, outboards and other small engines
- How long does E10 petrol last? Storage tips
- E15 gasoline: which cars can use it? (USA)
General information only. Always follow your vehicle handbook and the manufacturer's advice.