(image source: www.ethanolproducer.com)
During one of your visits to your local gas station, I’m sure you’ve noticed labels on the gas pumps stating that the gasoline that they offer is either a 10% (E10) or 15% (E15) blend of ethanol. What exactly is ethanol you ask? Ethanol is a renewable fuel made from various plant materials collectively known as "biomass." Some mowers, like the Z925M Flex Fuel from John Deere can handle ethanol blends of up to E85. The U.S. government has mandated the use of ethanol with gasoline to reduce the consumption and cost of gasoline. The United States continues to be the world’s top ethanol fuel producer.
Ethanol is perfectly fine for your automobile’s engine, but is it safe for your lawn mower? Most of the major lawn mower manufacturers approve the use of gasoline with a 10 percent ethanol blend. However, blends that use 15 percent ethanol or more can have adverse effects on your lawn mower’s engine. STIHL states: "STIHL outdoor power equipment is not designed for ethanol blends higher than 10% ethanol or E10." Similar statements have been released from the other manufacturers that we carry; Honda, Exmark, and John Deere.
The Outdoor Power Equipment Institute (OPEI) suggests that you avoid using a gasoline mixture labeled as E15 in your mower because the fuel can corrode and seriously damage fuel systems that are not designed for use with E15. Additionally, overheating can result from the use of E15 because E15 fuels burn significantly hotter than the E10 or ethanol-free gasoline. Ethanol blends can absorb water from the air, and under humid conditions, can make starting your lawn mower extremely difficult. Keep in mind that most lawn mower gas tanks and carburetors are vented to give the ethanol the opportunity to absorb water from the atmosphere. Due to this absorbent nature, ethanol can cause your mower to stall by gumming up fuel system of small two-stroke motors.
Also important to consider is that, generally speaking, the higher the ethanol content, the lower the shelf life of the gasoline. Ethanol-free gasoline has a shelf life of approximately three months, while gasoline with an ethanol blend lasts merely a month or less.
Lawn equipment manufacturer Toro suggests the use of ethanol-free gasoline. The company also recommends that you use unleaded gasoline with an octane rating of at least 87. Toro warns that damage to the engine, fuel system, or carburetor due to the use of unapproved gasoline in your lawnmower may not be covered by the warranty. Toro also points out that you can use biodiesel in their diesel-engine mowers. Environmental benefits of biodiesel include lower greenhouse gas emissions compared to petroleum diesel fuel, its biodegradable properties, and the fact that it’s nontoxic.
So, next time you fill up your lawn mower be sure to be conscious of what you’re fueling up with. Strongly consider going to a gas station that offers E10, or even better - ethanol-free gasoline. If you own a diesel-engine lawn mower, seek out biodiesel fuel. Avoid purchasing any gasoline that has an ethanol blend exceeding 10 percent.
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