Ask/Answered: What happens if I put ethanol (E85) in a standard-fuel vehicle?
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Ask/Answered: What happens if I put ethanol (E85) in a standard-fuel vehicle?


Ask/Answered is a weekly feature for reader-submitted questions. Follow the blog online at

I put fuel designed for flex-fuel vehicles in my standard-fuel car. Should I panic?

For both environmental and monetary reasons, consumers are increasingly attracted to flex-fuel vehicles that can use fuel containing higher percentages of ethanol, a fuel created from biomass (in the United States, usually corn).

On average, E85 (fuel containing up to 85% ethanol) is about 30 cents per gallon cheaper nationwide than the E10 blend (10% ethanol) that most of us put in our cars, according to the Renewable Fuels Association.

But what happens if you accidentally grab the wrong nozzle at the gas station and put E85 in a car engine not designed for it?

According to sources like and ABC Insurance Agencies, it isn’t that big of a deal as a one-time mistake. The biggest problem is that ethanol can have a corrosive effect on the fuel system over an extended period of time.

Drivers can alleviate this in two ways. First, consider driving the vehicle a long distance to use up the fuel as quickly as possible. Second, repeatedly top off the tank with standard gasoline, which will mix with the remaining E85, reducing the ethanol concentration of the fuel in the tank.

Regardless, your car will probably be OK if you don’t fill it with E85 repeatedly. Your check engine light will likely come on.

Using standard fuel in a premium-fuel car just one time also isn’t catastrophic, experts say. You’ll probably notice that it doesn’t accelerate as fast, loses gas mileage and possibly experiences “spark knock,” a high-pitched pinging or rattling sound.

In both cases, don’t panic, just don’t do it again.

If you’re looking for a legitimate reason to panic, here’s one: mixing up gasoline and diesel fuel. A gasoline-fuel vehicle likely won’t be able to ignite the diesel, so it will stop running. Meanwhile, running a diesel vehicle on gasoline can create catastrophic problems, such as engine damage.

If this mistake occurs, call a tow truck and have a mechanic completely drain the fuel from the vehicle’s systems before refilling it, experts advise.

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The best questions will be featured in weekly Ask/Answered columns online and in print.

Daniel Walmer covers public safety for The Sentinel. You can reach him by email at or by phone at 717-218-0021.


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