Does ethanol damage lawn mower engines?

As lawn care business owners, we strive to provide proper maintenance for our lawn equipment. Equipment engine oil is changed regularly. Air filters are cleaned and/or replaced when they become dirty. Lubrication is performed on schedule as outlined in owners’ manuals.

In addition to routine maintenance, there are many other tips we can follow to help extend lawn equipment life. We cover many tips within the pages of our Lawn Care Business Guidebooks.

One of the simpler actions we can take, on a daily basis, is use of high quality gasoline. High quality does not necessarily mean high octane. High quality, in many people’s opinion, means a lack of impurities.

There is a gas station not far from our business location that charges a few cents per gallon less than competing station. However, the gas station is more than 40 years old and it looks dilapidated. A gas station in such poor condition makes us wonder about the condition of their fuel tanks. If their tanks are corroded and contain residue from years of being underground, could those impurities find their way into our gas tanks?

Though ethanol is not considered an impurity to industry insiders, many small engine mechanics speak up about damage caused by ethanol. According to an MSNBC article on damage to small lawn mower engines caused by ethanol in gasoline ethanol attracts moisture which prevents oil within lawn care equipment from doing its proper job. This moisture reacts with rubber and plastic fittings and hoses. As these parts deteriorate, they may clog openings within the engine and can cause a shellacking on pistons resulting in reduced lubrication. All this is according to small engine experts.

Don’t rely strictly on experts though, read the many comments in this blog from dealing with the hazards of using ethanol blended gasoline in many different types of engines.

In the southern states where we live, 10% ethanol has been a fact of life since early 2008. Though we have heard horror stories of damage done by ethanol, we rarely have a choice other than to use an ethanol gasoline blend.

Times are beginning to change, though, and we see signs that gas stations are offering 100% gasoline again. In fact, a brand new gas station with brand new tanks, less than half a mile from the old dilapidated gas station offering 10% ethanol, has just opened. This new gas station does not add ethanol and offers pure gasoline.


Ahh…no contamination and no ethanol. Our lawn mowers and two-cycle leaf blowers, weedeaters, and other lawn care equipment will run “clean” once more.

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