How to Protect Small Engines From Ethanol Fuel

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Ethanol is commonly mixed with gas, and is available at most gas stations. Large engines are more sophisticated than small engines, and thus can handle the chemical make-up of ethanol more effectively. Newer engines, whether large or small, are also being tailored to use an ethanol blend efficiently.

Although it can be attractive to use an ethanol blend, due to its lower price, not all engines are yet made to accommodate for the differences between ethanol and straight gas. Small engines are particularly vulnerable to a number of issues related to ethanol use, including clogging, deteriorating parts, and water contamination.

Avoid using ethanol blends in small engines when possible. Use straight gas.

Use fresh gas. Buy from busy gas stations, and replace the gas in small engine tanks every two to four weeks. Don't use an ethanol blend that has sat more than 90 days.

Install a 10-micron water separating fuel filter if your engine doesn't have one. Newer engines may already have these. Ethanol binds with water, so this helps to correct the issue of an ill-running engine due to water in the fuel.

Replace the fuel filter regularly. The recommended replacement time is every 50 to 100 hours of use.

Don't run the engine on a near-empty tank. Water settles to the bottom.

Upgrade your engine. Certain parts are more susceptible to degradation from ethanol, so upgrading these parts to ethanol.-friendly ones prevents clogging from the sediment produced by degradation. Parts include gas tanks, hoses, gaskets, certain carburetor components, and any "soft" parts that come into contact with gas.

Keep the engine in good running order. Regular tune-ups help to relieve engine stress, and thus to keep it running longer, even with the use of ethanol. Out-of-tune small engines that use ethanol may see more issues than an out-of-tune engine using gas.


  • Some are in disagreement that ethanol can cause issues in any engine, and believe that there is no reason for concern. Use your own discretion, though it may still be beneficial to follow these precautions regardless.


  • Recent changes in EPA regulations are raising the percentage of ethanol legally allowed to be blended in gas. Previously, this was 10 percent. As of October 2010, this is being raised to 15 percent, so precautions to protect small engines are advised.


About the Author

Jennifer Thompson started editing for her own online business in 2001, then began online editing and writing for others in 2005. Her articles have been published with "Sportsman's News" on Fox News and for a number of other successful ventures.

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