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So you’ve heard that some gasoline contains up to 10% “Ethanol.” And maybe you’ve even been told that “evil” ethanol is bad for outdoor power equipment and certain car motors. But you’re still a bit fuzzy on what exactly ethanol is and what is so evil about it. Luckily, MotorBiscuit is here to make all things clear.

Ethanol is just a fancy chemical name for alcohol. Yup, that kind of alcohol. Pure ethanol is a colorless flammable liquid produced by using yeast to ferment sugar. Drinks that we colloquially call “alcohol” contain a percentage of pure ethanol but are mostly other liquids, such as the grape juice that was fermented to make the ethanol/alcohol.

So why are we wasting alcohol in our fuel? And what’s wrong with pouring it into every engine? I mean, cars can’t exactly get drunk.

Sign warning of up to 10% ethanol fuel mixture on a gasoline pump.
Ethanol fuel sign | Ablokhin via iStockPhoto

Very long story short: You can only get gasoline by refining crude oil pumped out of the earth. But you can make the ethyl alcohol for ethanol fuel by fermenting and distilling a vast array of plants. In the U.S., we make a ton of ethanol fuel additive by fermenting and distilling surplus corn. That’s right, the same stuff that goes into whiskey. But there are some other upsides to ethanol fuel as well.

You certainly don’t want to drink a shot of E10 (gasoline and 10% ethanol), but even E85 gasoline is far from a safe drink. Why? It is purposely mixed with at least some poisonous gas so no one will be tempted to take a swig.

But here’s the deal, ethanol may cause corrosion to your engine with repeated use. This can be even worse in older cars. In fact, only new cars can successfully run on gasoline/ethanol mixtures in the first place. New engines with carburetors, such as many lawnmowers, also need “pure” fuel with no ethanol. Why? Because the ethanol will damage those carburetors.

There are situations where ethanol-rich fuel is better, such as in motorsports. This is one reason the latest Dodge Demon, the “170” is engineered for more horsepower with ethanol gasoline.

Next, learn all about the chemistry behind ethanol fuel and see how it burns cleaner than regular gasoline in the video below: