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Does E85 Go Bad?

Jeep Wrangler

Does E85 Go Bad?

Does E85 fuel go bad? This is one of the most common questions our customers ask us. The short answer is yes. Like all fuels (including gasoline), E85 can go bad if it sits long enough. Here's why:

  • Toluene
  • Cumene
  • Xylene
  • Heptane
  • Benzene

Some of these compounds are flammable, for example. Let's say cumene, which is one of the flammable compounds, evaporates. This reduces the ethanol's ability to power the engine. All the compounds in ethanol work together to provide the ideal type of fuel for vehicles. If the E85 loses some of these compounds via evaporation, it won't work quite as well anymore.

E85 Can Absorb Moisture From The Air

E85 fuel is hygroscopic. The ethanol in E85 can absorb moisture from the air. When that happens, the moisture affects the fuel's ability to power the engine. When there's enough water mixed in with E85, the fuel is no longer good to use. (Read about corrosion in this article.)

How Long Does E85 Last?

Flex fuel that contains a higher ethanol content won't last as long as flex fuel that contains a lower ethanol content. For example, E85 contains 85% ethanol, and E20 contains 20% ethanol. That means E85 won't last as long as E20.

The good news is if E85 evaporates and/or absorbs moisture, it doesn't happen right away. It happens over the course of months or even years. Most of the time, the fuel is burned off long before it breaks down or absorbs water.

There Is No Concrete Expiration Date On E85. Does E85 Go Bad?

It can last years, or it can go bad in as little as three months. Its longevity depends on a lot of factors, including:

  • The amount of moisture in the air
  • Whether the fuel system is sealed

E85 Will Last Longer If Your Vehicle’s Fuel System Is Sealed

Almost all modern fuel systems are sealed. This is a good thing because:

  • A sealed fuel system doesn't let any air or moisture in. Therefore there's no moisture for your E85 gas to absorb.
  • Your E85 gas can't evaporate because it has no way to leave a sealed fuel system.

So if you have E85 sitting in your fuel system, chances are it's still good. If you're storing E85 outside of the vehicle for more than 6 weeks, be sure to use a metal container. E85, like gasoline, eats away at plastic over time.

How To Know If Your E85 Fuel Has Gone Bad

There are ways to tell if your E85 fuel has gone bad. Here are some signs to look for while driving:

  • Reduced gas mileage
  • Stalling
  • Engine running rough
  • Difficulty starting up
  • Sluggish acceleration

If you're looking at E85 in a container, there are a couple of signs that it has gone bad:

  • A layer of water at the bottom of the container
  • A reduction in the amount of gas left (this is a sign that evaporation has occurred)

When in doubt, replace your E85 gas with a fresh batch. Driving with a bad batch of E85 can cause issues within your engine.

June 9, 2021

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