Can you use E15 gas in a motorcycle? What riders should know

No, you should not use E15 gas in a motorcycle. E15 is approved only for flex-fuel vehicles and cars and light trucks of model year 2001 and newer, and the U.S. Department of Energy lists all motorcycles among the vehicles it is not approved for.

Most motorcycles are designed for gasoline with up to 10% ethanol (E10), and many older bikes do best on less. Here is why the limit exists, what to do if you fill up by mistake, and how to avoid E15 at the pump.

Can you use E15 gas in a motorcycle?

No. The Department of Energy's Alternative Fuels Data Center says E15 is approved for flexible fuel vehicles and conventional vehicles of model year 2001 and newer, and it specifically names "all motorcycles" as not approved. The same list excludes heavy-duty engines, boats, snowmobiles and small off-road engines such as lawn mowers.

That applies to new and old motorcycles alike. A 2025 sport bike is not covered by the car approval just because it's newer than 2001.

Your owner's manual will say the same thing in its own words. Most list a maximum ethanol content, usually 10%, and some recommend lower.

What is E15?

E15 is gasoline blended with up to 15% ethanol. Regular U.S. pump gas is typically E10, meaning up to 10% ethanol. Some stations sell E15 under names like "Unleaded 88" because its octane rating is often 88.

Fuel	Ethanol content	Approved for motorcycles?
E0 (ethanol-free)	0%	Yes
E10 (most pump gas)	Up to 10%	Yes, for most bikes; check your manual
E15 / Unleaded 88	Up to 15%	No
E85 / flex fuel	51% to 83%	No

Why isn't E15 approved for motorcycles?

Ethanol behaves differently from gasoline, and more of it means bigger effects. Concerns for motorcycles include:

• Leaner mixture. Ethanol contains oxygen, so more of it leans out the air-fuel mix. Bikes with carburetors or simple fuel maps may run hot, hesitate or stall.
• Material compatibility. Some rubber hoses, seals, gaskets and plastic or fiberglass tank parts were not designed for higher ethanol and can swell, harden or degrade.
• Water absorption. Ethanol attracts moisture. In a bike that sits, that can lead to corrosion and phase separation, where water and ethanol drop to the bottom of the tank.
• Higher operating temperatures. Lean running can raise engine temperatures, which matters most on air-cooled engines.

Motorcycles weren't part of the testing that led to E15 approval for cars, which is why they fall outside it.

What happens if you accidentally put E15 in your motorcycle?

Don't panic. One accidental tank is unlikely to cause immediate damage on a modern fuel-injected bike. Still, it's not approved fuel, so:

1. Don't top it off with more E15. If you notice right away, it's best not to ride until you can drain or dilute it.
2. If you must ride, ride gently. Avoid heavy loads, high rpm and long climbs.
3. Refill with E10 or ethanol-free gas as soon as the tank is low, to dilute what remains.
4. Watch for symptoms such as hesitation, surging, hard starting, pinging or running hotter than normal.
5. Don't store the bike on it. If the bike will sit, drain the tank and refill with the correct fuel.

On older carbureted bikes, or if you filled a nearly empty tank with E15, draining is the safer choice. A shop can do this if you're not set up to handle gasoline safely.

How to avoid E15 at the pump

Read the label

E15 dispensers carry an orange warning label that says the fuel is for flex-fuel vehicles and 2001 and newer passenger vehicles only, and that it's prohibited in other vehicles and equipment. Read it every time at an unfamiliar station.

Watch for shared-hose pumps

This is the less obvious trap. At some stations, E10 and E15 come out of the same hose and nozzle. The EPA explains that on these co-dispensing pumps, the first few gallons of E10 can contain slightly more than 10% ethanol, because leftover E15 from the previous customer is still in the hose. A 4-gallon minimum purchase on those pumps is meant to keep the total below 10%. That's a problem for a motorcycle with a 3- or 4-gallon tank.

The EPA adds that motorcyclists can buy any amount of gasoline from a dedicated E10 pump. It also says it isn't aware of a single U.S. gasoline station that doesn't offer either E0 or E10. In practice:

• Look for a pump with its own hose for each grade.
• If a pump has one hose for several grades and a 4-gallon minimum sign, use a different pump.
• Ethanol-free gas, where available, usually has its own dedicated pump.

Don't assume premium is ethanol-free

Most U.S. premium is E10. Whether your bike needs premium at all is covered in does my motorcycle need premium gas. Only pumps marked ethanol-free or E0 are free of ethanol.

Symptoms that can follow a tank of E15

If you've filled up and aren't sure what went in, these signs suggest the fuel may be the issue:

• Hesitation or a flat spot when you open the throttle
• Surging at steady speeds, especially on carbureted bikes
• Hard starting when hot or cold
• Pinging or knocking under load
• Running hotter than usual on the temperature gauge, or more heat from an air-cooled engine
• A warning light on bikes with an oxygen sensor, as the ECU tries to correct a leaner mixture

Many of these overlap with other fuel and ignition problems. If the symptoms started right after a fill-up, note the station and pump. That makes it easier to sort out with a shop.

Storage, ethanol and phase separation

Fuel that sits is where ethanol causes the most trouble. Ethanol absorbs water from the air, and once it holds enough, the water and ethanol can separate from the gasoline and settle at the bottom of the tank, right where the fuel pickup sits. A bike that starts on that layer can run very poorly or not at all. Higher ethanol content makes this more likely, which is another reason never to store a bike with E15 in the tank.

Does E15 void a motorcycle warranty?

It can be a problem. Manufacturer warranties generally cover defects, not damage caused by using fuel the owner's manual says not to use. If fuel-related damage is traced to E15, a claim may be denied. Read the fuel section of your manual and warranty booklet, and keep receipts if you're ever unsure what went in the tank.

Long-term ethanol issues on older bikes

Even E10 can cause trouble on older bikes and bikes that sit. Common problems include gummed-up carburetor jets, cracked fuel lines and corroded tanks. If your bike is from the 1990s or earlier, or sits for months at a time, consider ethanol-free gas when it's available, and use a stabilizer during storage. Our guides to cleaning a motorcycle carburetor and winterizing a motorcycle cover the details.

Fuel lines that become soft, cracked or damp are a fire risk. If you smell gas, read our guide to a motorcycle leaking gas before riding.

When to see a mechanic

Get the bike checked if:

• You filled a mostly empty tank with E15 and the bike runs poorly
• It hesitates, surges, pings or runs hot after a fill-up
• You see swollen, cracked or wet fuel hoses, or smell fuel
• The bike sat with E15 or old ethanol fuel in it for months
• It won't start after storage (see why a motorcycle won't start)

A shop with motorcycle diagnostics equipment can drain the tank, check the fuel system and clear any fault codes. E15 is especially common in the Midwest, so riders there should be extra careful at the pump.