What Every Enthusiast Should Know About Pump Gas and E85 Fuels

Ethanol has become part of our daily lives in the regular fuel we put in our vehicles. The typical consumer is using E10 enhanced fuel, which is mandated by the EPA, and contains 10-percent ethanol. That ethanol has some important properties of  concern to us in the performance world. For example 87 octane fuel, that is processed to the E10 standard, is actually 83 octane gasoline, the extra 4 points of octane to get to 87 come from the addition of ethanol. This holds true for 89, and 91 (or 93) octane fuels as well.

E85 is also increasingly popular within the performance community as “cheap” alternative to race fuel. While octane rating varies, E85 is typically good for somewhere between 100 and 105 octane. There are obvious benefits to this in high compression, or forced induction applications, chiefly it’s cheap high octane fuel at the pump, rather than from a barrel or race track.

Corrosion inside a carburetor after exposure to ethanol blended fuels.

The ethanol content in both regular pump gas and E85 is something that as enthusiasts and drivers we need to be aware of. Ethanol is derived from ethyl alcohol, it’s added to fuel as an oxygenate to improve emissions. Ethanol is also hygroscopic. This means it absorbs water, it can actually pull water from the humidity in the air. Combining oxygen and water often leads to corrosion on many different types of metal.

With these things in mind, it’s important to consider what you’re doing with your performance or collector car when you store it this winter, and what you may need to do to ensure you’re not replacing parts as often during the summer. Since ethanol is an alcohol based product, running this type of fuel requires many of the same considerations as running methanol, or another alcohol based race fuel.

Fuel system components, not designed for ethanol blended fuel are susceptible to the negative side effects of running it,” says Speed. “The higher the ethanol content in the fuel, the more detrimental the effects will be. -Lake Speed Jr, Driven Racing

We spoke with Driven Racing’s Lake Speed Jr, about the proliferation of ethanol in our fuel, and the popularity of E85. “Fuel system components not designed for ethanol blended fuel are susceptible to the negative side effects of running it,” says Speed. “The higher the ethanol content in the fuel, the more detrimental the effects will be.”

The entire fuel system must be considered with any ethanol blended fuel. Viton seals, which are impervious to the degradation caused by exposure to alcohol are mandatory. Fuel lines should also be rated for use with this type of fuel, as should fuel pumps, regulators, rails, tank seals, and even the fuel tank itself.

Most mechanical fuel pumps weren’t designed for use with any type of ethanol at all, even just E10. The corrosive nature of the additive will actually cause fuel pump wear issues according to Speed. “We have found in our testing that zinc, magnesium, aluminum, and steel, the most common metals used in automotive applications, are susceptible to corrosion from ethanol.”

Zinc is used as an internal coating on most carburetors. During the chemical reaction with ethanol, zinc is used as the sacrificial anode, being corroded away, leaving zinc oxide behind. From there, the corrosion doesn’t stop, ethanol will continue to eat away at the remaining metal, causing further damage.

There is also the issue of the deposits left behind. Speed says With ethanol being bio-based, it’s going to leave more deposits behind. These deposits block passages in carburetors and fuel injectors, clog jets, and if left alone continue to build up and cause problems.

Fuel injected applications aren’t necessarily immune to these effects either. “Most people assume that modern fuel injectors are safe for use with ethanol. Unless the manufacturer specifically says the injector is manufactured for use with E85, you should assume it isn’t.” Speed also points out that in forced induction applications, where E85 has become increasingly popular with many enthusiasts, the additional heat generated can compound the issues of deposits and fuel deterioration.

Most people assume that modern fuel injectors are safe for use with ethanol. Unless the manufacturer specifically says the injector is manufactured for use with E85, you should assume it isn’t.

Products have existed for a number of years to “neutralize” or “remove” ethanol from fuel. Speed says that care must be taken when choosing these types of treatments. He says, simply removing the ethanol from fuel or neutralizing it in some manner can drastically alter the fuel’s characteristics. “The worst thing you can do is put something in the fuel that alters its characteristics,” says Speed. Removing the ethanol will change the fuel’s octane, can alter the specific gravity, and other characteristics. This not only goes for so called ethanol treatments, but also for those that promise to remove moisture from the fuel. Speed says in removing that water you may also be removing the ethanol since its hygroscopic properties attract it to the water.

Driven Racing Oil has used their resources and experience in the racing world to develop the company’s Carb Defender product. Carb Defender protects components in the fuel system from the harmful effects of ethanol, without removing the ethanol itself. It also helps to clean up the deposits left behind. All of this is possible without changing the specific gravity, octane, or burn properties. The product is compatible with both carbureted and fuel injected engines, and the company is looking into an EFI specific version.

Speed says with any fuel additive there are a few key things consumers should look for:

  • Prevents corrosion and stabilizes fuel
  • Keep fuel from going bad as quickly. The hotter and higher the pressure, the faster the fuel degrades.
  • Deposit protection and control
  • Oxidation stability

With winter setting in for most of the country, many of us are storing our project and race cars until spring, or planning our next round of winter upgrades. Before you close the garage door and pull on the car cover, it would be wise to run some Driven Carb Defender through the fuel system in preparation for your car’s long winter nap, and continue its use through the summer driving season to avoid problems.

Article Sources

About the author

Don Creason

Don Creason is an automotive journalist with passions that lie from everything classic, all the way to modern muscle. Experienced tech writer, and all around car aficionado, Don's love for both cars and writing makes him the perfect addition to the Power Automedia team of experts.
Read My Articles

Classic Street Rods in your Inbox

Build your own custom newsletter with the content you love from Rod Authority, directly to your inbox, absolutely FREE!

Free WordPress Themes
Rod Authority NEWSLETTER - SIGN UP FREE!

We will safeguard your e-mail and only send content you request.

Rod Authority - The #1 Authority for Street and Rat Rods

We'll send you the most interesting Street Rod articles, news, car features, and videos every week.

Rod Authority - The #1 Authority for Street and Rat Rods

Rod Authority NEWSLETTER - SIGN UP FREE!

We will safeguard your e-mail and only send content you request.

Rod Authority - The #1 Authority for Street and Rat Rods

Thank you for your subscription.

Subscribe to more FREE Online Magazines!

We think you might like...



Hot Rods & Muscle Cars

Classic Chevy Magazine

Corvette Enthusiasts

Rod Authority - The #1 Authority for Street and Rat Rods

Thank you for your subscription.

Subscribe to more FREE Online Magazines!

We think you might like...

  • Hot Rods & Muscle Cars
  • Classic Chevy Magazine
  • Corvette Enthusiasts

Rod Authority - The #1 Authority for Street and Rat Rods

Thank you for your subscription.

Thank you for your subscription.

Rod Authority - The #1 Authority for Street and Rat Rods

Thank you for your subscription.

Thank you for your subscription.

Loading