Can ethanol damage your engine?

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Author's Note: Can ethanol damage your engine?

I love popcorn and buttery, salty grilled cobs as much as the next girl -- but at least I admitted to myself, long ago, that corn is not actually a vegetable. It's as sweet as candy, and features just as much nutritional value, which is probably why it's so often processed and used for confectionary purposes. But about 40 percent of the 2012 domestic corn crop was designated for fuel production [source: Bowman]. Fuel might actually be a more noble objective than food, in theory.

But even if ethanol was harmless to a car, it falls short in other areas. It's a biofuel, a category that implies there's some kind of environmental benefit as a result of its use. There are other kinds of biofuels besides ethanol; and as I mentioned, there are also other types of ethanol besides those derived from corn. And as it turns out, corn ranks among the least environmentally friendly biofuels in terms of greenhouse gas emission reduction. Corn ethanol hardly reduces a car's toxic emissions at all -- in fact, 3 percent is about the best that can be expected [source: Garrett].

Other sources, like sugar and hemp, give much better statistics (upwards of a 50 percent reduction in greenhouse emissions). Unfortunately, sugar cane ethanol comes from Brazil and is saddled with high import tariffs, and it's still illegal to raise hemp in the United States (even the industrial-grade stuff that doesn't have any psychoactive benefit or pleasurable nefarious purpose).

It's unclear (at least to me) if other types of ethanol have the same engine-clogging properties as corn. I won't go so far as to draw parallels between gasoline sludge and elevated blood sugar levels. But even though ethanol is increasingly pumped into our gasoline supply for purely political reasons, we can hope that reasonable alternatives might be considered ... eventually.

Related Articles


  • Allen, Mike. "Can Ethanol Really Damage Your Engine?" Popular Mechanics. Dec. 21, 2010. (Jan. 18, 2013)
  • Bowman, Zach. "AAA calls on US government to suspend E15 gasoline sales." Dec. 4, 2012. (Jan. 22, 2013)
  • Consumer Reports. "Automaker tests show damage to older car engines from running on E15 ethanol." May 17, 2012. (Jan. 17, 2013)
  • Evarts, Eric. "Warranties void on cars burning E15, say automakers." Consumer Reports. July 7, 2011. (Jan. 17, 2013)
  • Garrett, Jerry. "Corn Ethanol: Biofuel or Biofraud?" The New York Times. Sept. 24, 2007. (Jan. 22, 2013)
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