Mechanics Corner: Common Ethanol Myths

Automotive advice from The Under the Hood radio show

We’ve been talk show hosts for 30 years now, but we’re also mechanics and parts people working in a shop and selling parts to consumers. This gives us a hands-on perspective as to what parts and systems are working or failing and why. Working on engines is more than just replacing parts; a quality repair means finding out why it failed and correcting that issue before putting the vehicle back into service.

Over the decades we have seen a lot of issues! From large trucks to small engines and everything imaginable in between. Many of our customers got advice from another place or came to their own conclusion only to find out the problem was completely different. One of the top concerns customers come in with is related to the fuel. “Maybe I got some bad fuel” or specifically, “could it be the ethanol I’m using?” Let’s go through some of the myths we have seen customers mention when coming in for repairs.

1. Ethanol caused my gas to freeze and my car won’t start.

Myth: During cold weather the ethanol in the fuel caused water to be absorbed and the tank had so much water in it that the fuel could not flow.

Fact: The car did not have a fuel problem at all, it had a faulty fuel pump likely caused by the dirty fuel filter which had never been replaced and the vehicle had over 100k miles on it. When the pump was removed from the tank there was no sign of water in the tank.

2. My car won’t run right, and I can hardly drive it. It stalls and the check engine light is on. My mechanic said it was the ethanol blends I’ve been using.

Myth: Using ethanol is causing the poor running all by itself. We inspected the car and with 140k miles found the spark plugs and coils worn-out, the air filter nearly plugged and a failed mass air flow sensor.

Fact: After replacing these parts, the car ran like new, so this was a maintenance issue and except for the spark plugs these parts do not have any contact with the fuel.

3. Ethanol causes my truck to overheat on hot days.

Myth: Using ethanol causes an engine to run hotter. This is a 2001 Ford truck with a V8 engine and fuel injection. A closed loop fuel injected engine can add or take away fuel to give it the perfect mixture and keep cylinder temps in check when used in quantities recommended by the manufacturer. Ethanol has less BTUs than gasoline so it by nature burns cooler so we know fuel can’t be the cause if it truly has e15 in the tank.

Fact: A test drive did show overheating when outside temps were over 80 degrees at highway speeds and a close look at the engine revealed that there was a heavy build up of dirt in between the radiator and A/C condenser where it could not be seen. We washed it out and the car was back to normal with no other changes.

These are just a few of the things we have seen hands-on in our shop. These repairs were all done several years ago, and no further issues have developed with them due to fuel.

The Under the Hood radio show is America’s Favorite Car-talk show heard on over 230 stations and podcast. The Motor Medics, Russ, Chris and Shannon, are three great friends having fun and offering a wide range of automotive advice without the aid of in-studio computers or reference guides.




Vital is a news & media resource published by POET, presenting a variety of stories with the thought leadership one expects from the largest, most forward-thinking bioethanol producer.