Ask the Beaverton Car Guy: What’s wrong with ethanol fuel?

By Larry “The Car Guy“ Fergusonbrg-the-beaverton-car-guy-columnist-larry-fergusen-2

Hello Beaverton Readers!

This month’s article is all about the damage ethanol fuel can do to vehicles. Oregon gets the poorest quality fuel in the nation. It does not regulate the fuel it receives to retail and ethanol fuel simply adds to the list of problems that plague many cars. There is still non-ethanol fuel available but it is difficult to find and costs around $4 per gallon.

10% ethanol/90% gasoline mix (E10)

We all have seen the signs and stickers on gas pumps everywhere stating that there is 10% ethanol added to our gasoline. This Mixture of 90% gasoline and 10% ethanol is often referred to as E10 or “gasohol”. We usually just fill our tanks up and go, not ever giving a thought to what effects burning the added ethanol in our engines may have. Does ethanol damage engines? Do you lose power, performance, and MPG with ethanol?

Why is ethanol added to our fuel in the first place?

The answer to this question goes back to amendments made to the “Clean Air Act” in 1990. This amendment stated that gasoline be oxygenated to cut down on Carbon Monoxide emissions. The first additive that was used to do this was Methyl Tertiary Butyl Ether (MBTE). MBTE had a very strong turpentine smell and was proven to contaminate ground water. MBTE was replaced by ethanol around the year 2000.

Are there positive effects of ethanol in our gasoline?

Adding an Oxygenate Ethanol reduces carbon monoxide emissions thus reducing pollution but this reduction in pollution is really only noticed in engines that have a carburetor and are not computer controlled by a “closed loop” EFI computer system. Any vehicle that has Electronic Fuel Injection (EFI) uses at least one oxygen sensor to analyze the exhaust allowing the vehicle’s computer to make adjustments to control emissions so they benefit very little from an ethanol mixed fuel as far as an emissions reduction goes. The main reason we add 10% ethanol stems from the Bush administration’s push to reduce America’s dependency on foreign oil.

Debris in fuel / premature fuel breakdown.

There is always old fuel somewhere in the fuel system and after 30-60 days it deteriorates leaving behind gum and varnish throughout the system. Ethanol is a great cleaning agent and this is why ethanol is used in almost every bottle of carb / injector cleaner on the market. When you fill up your tank, the 10% fresh ethanol runs through your fuel system dissolving the gum and varnish causing a bunch of crud to flow through the engine clogging filters, injectors, carburetors, etc. All of this can lead to hefty repair bills.

Water in fuel.

Pure gasoline does not absorb water but ethanol will. Oil and gasoline are lighter than water so the water /ethanol mixture will stay at the bottom of your fuel tank. This can be a real problem because the water from the bottom of the tank is sucked up and sent to the engine raising temperatures that can cause damage. It gets worse too since the ethanol and water mix in E10 is a breeding ground for bacteria and fungi which just adds to the corrosion.

Loss of power, octane rating, performance and mileage from E10 gasohol.

Contrary to what most people believe, higher octane gas does not make your engine more powerful. Only if your engine is built for performance or racing with a higher compression rating do you need to use a higher-octane gasoline. Octane prevents gasoline from pre-igniting by slowing down the burn rate from an early damaging explosion to a slower more controlled burn. Ethanol lowers the octane rating to around 82 to 84 and this is too low for a gasoline powered engine to run efficiently and causes loss of power and engine damaging pre-ignition.  Ethanol produces about 34% less energy than the same amount one gallon of gasoline so in an E10 mixture you will lose 3% – 5% of your horse power and MPG.

Ethanol is corrosive.

I mentioned that ethanol is an excellent cleaning solvent but it is also a drying agent and can disintegrate plastic, rubber, some types of fiber glass, aluminum and magnesium. Any car or truck that is not a “Flex Fuel” vehicle is most likely not equipped with ethanol resistant parts. Neither would small engine devices like lawn mowers; motorcycles etc.

Thank You all for reading,

I hope this information is helpful. Remember that Ethanol fuel has a shelf life of a maximum of 60-90 days so it is not a great idea to fill the tank of a vehicle that is not used on a regular basis.

Larry’s specialty is locating cars, even hard to find cars, for everyday folk. He has been in the automotive industry for over 35 years and has several degrees in automotive technology. Email him at or call 503-930-1493