Everything You Need to Know About Ethanol in Gasoline

Everything You Need to Know About Ethanol in Gasoline

Fuel for equipment and vehicles has changed dramatically since the early 2000s. Before that time, non-ethanol gas was the standard for any gas-powered engine. When adding ethanol as a form of oxygenating fuel was released to the public, it was met with skepticism. How will it react with older vehicles and equipment? Will engines go bad faster? Does ethanol lower the octane of the fuel? Should I keep using non-ethanol gas in my lawn equipment?

These were all valid questions that couldn’t be overlooked. The short answer is that using non-ethanol gas in lawnmower equipment will reduce the required maintenance of the mower and extend the life of the engine if all of the other maintenance is properly performed.

To understand that answer, it’s important to understand what ethanol is, what it does when paired with gasoline, and what the effects are on your lawnmower. (The same goes for any gasoline-burning 4-stroke engine)

Why Ethanol is Used to Oxygenate

Oxygenation of gas has been performed by gas manufacturers since the early 1990s as a way of reducing emissions of gas engines. A chemical named MTBE was added to gas as the oxygenating compound. A more environmentally friendly solution to oxygenate fuel was developed and released a decade later in the form of ethanol. When going through the combustion process, ethanol produces cleaner emissions than MTBE. Another reason ethanol is now used is that its manufacturing process requires less energy to produce than the energy that ethanol provides. This is not the case with MTBE.

Ethanol Makeup

Ethanol’s purpose is primarily to oxygenate the gas. Contrary to popular belief, ethanol is not only made from corn but also contains what the Environmental Protection Agency (EPA) lists as “biomass”. Biomass is a mixture of plant matter from algae, grass, trees, etc.

When the biomass is manufactured to form ethyl alcohol, the result is a fuel source that has the equivalent of 113 RON (Research Octane Number). Because of ethanol’s high octane, it is very desirable for mixing with the fuel. Less manufacturing energy can be used to produce fuel at a lower octane than 87, and ethanol can be mixed in to achieve the 87 RON rating. The standard at this time is 10% ethanol and 90% gasoline, but 15% and 85% ethanol are commonly available.

Ethanol’s Effect on Gas

On paper, ethanol seems great. It is made from sustainable products and requires less manufacturing energy than gasoline. However, ethanol has some negative effects when combined with gasoline.

Lower Gas Mileage

When combined with gasoline, ethanol reduces gas mileage of engines by an average of 3%. An engine running e85 gas can expect a reduction of 7-8% when compared to regular gasoline. This is due to the lower energy density of ethanol. To match the energy density of gasoline, an engine has to consume more fuel, hence having less mileage per gallon of gas used.

Lawn equipment’s version of mpg is running hours. Using ethanol-blended gas roughly equals a 3% increase in fuel usage per hour.

Important Tip for e85 Gas: Do not put e85 in engines not designed for it. Because of the lower energy density, a lot more e85 is required to run an engine than pure gasoline. If putting e85 in an engine not designed for it, it will cause high combustion temperatures (and a lot of other simultaneous issues) and eventual failure of the engine.

Damaging to Parts

Ethanol is corrosive to metals and causes plastic parts to become brittle and break apart. Newer vehicles have been designed to solve this issue, but older vehicles are particularly susceptible to the damage caused by ethanol-blended gasoline.

For lawn equipment, no equipment is designed for use with ethanol-blended gas. The EPA’s stance on recommending pure gasoline for lawn equipment remains in effect almost 20 years after e10 gas was mandated.

Water Absorption

Ethanol is highly attracted to water, and when blended with gasoline, does not stop water from being absorbed into the ethanol from the humidity in the air. The major problem this presents is that water cannot be compressed by the pistons in engines. If a lot of water were introduced into the engine, it would cause engine failure.

Additionally, small amounts of water making its way into the engine further lowers octane ratings, causing worse gas mileage and problems when the engine is in a high-load situation. (like going up steep hills or towing)

Fuel Life

Ethanol fuel has a shorter life span than gasoline due to phase separation, which is the term for the ethanol separating from the gasoline. The recommended lifespan of ethanol-blended gas is 30 days, while the average lifespan of gasoline is approximately 1 year.  Stabilizers can help (as outlined in my article HERE) but cannot stop phase separation.

What Type of Gas for Lawn Equipment?

Since this is a home-related site, I am focusing on lawn equipment for my recommendations. As mentioned above,  20 years after the mandate of e10 gas, the EPA still recommends non-ethanol gas and no higher than e10 be used in lawn equipment.

Non-ethanol gas causes lower combustion temperatures in the engine, allowing internal engine components to not be as stressed as with higher temps. Any time stress on components is lessened, they will last longer. However, it is more difficult to find non-ethanol gas and slightly more costly.

A tip for finding non-ethanol gas is to do a simple online search. Depending on your region of the country, you can find the proper non-ethanol gas station. Where I live, I go to major gas stations that have non-ethanol pumps for boats. I pump 10 gallons at a time into 2, 5-gallon safety cans. Ten gallons lasts me half a season, and only costs a total of $3 more than filling up with 10 gallons of e10 gas.

Ethanol has its place and is good when an engine is designed to use it. The issue is when it’s mandated for use without consideration to the effects on the consumer. I chose to not mention the regulations behind ethanol production, but if you are interested, you can search online for those. With ethanol use increasing and pure gasoline production decreasing, a solution needs to be presented to save consumers from having ruined equipment due to ethanol use. Will this happen? Only time will tell…

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