Mechanics Corner: What You Need to Know About Using E15

Ethanol has been around in our fuels for a long time. Since the 1980s, fuel composition has consistently been changing. The latest change is more ethanol in the fuel supply, due to ethanol’s economic, environmental and performance benefits. It’s a natural progression, along with improvements in engine technology. In May 2019 the Trump Administration approved year-round sales of E15, a fuel blend with 15 percent ethanol. With that change, our Under The Hood radio show listeners have been asking several great questions about E15. Here are the top five:

1. Is E15 good for my engine, or will it harm it in any way? 

Ethanol has been added to gasoline in the U.S. fuel supply for decades, mostly at 10 percent and now at 15 percent. Drivers have been choosing it for its price point and have found it to work almost identically to non-ethanol gasoline when used at 10-15 percent. Some of the benefits, besides being much cheaper in most cases, are a cleaner-running fuel system and cooler cylinder temps. Many folks have their own opinions, but as full-time mechanics and users of the fuel this is what we are seeing.

2. What kind of car can we run E15 in? 

E15 has been certified for use in any gasoline-powered car with a U.S.-certified emissions system from 2001 or newer, whether it’s flex fuel or not. To be clear, 90 percent of all vehicles on the road today fall into this 2001-and-up category, so chances are that’s your vehicle. Many people have used it in older cars too, but use in 2001 and newer has been tested and approved by the Environmental Protection Agency and Department of Energy. Older models were not tested due to variability and age.

3. Can I save money using ethanol?

Yes, you can. Just look at the pump price and you will notice a significant difference between non-ethanol fuel and ethanol blends of E15. The cost savings for E15 range from 5 to 10 cents better than E10, and 30 to 40 cents better than a non-ethanol fuel. Some people may tell you that they see many miles per gallon difference between the fuels, but we would say, try it yourself and you make the decision. 

4. I’m concerned about the planet and pollution. Is ethanol any cleaner than gasoline? 

Ethanol is cleaner-burning than gasoline by its nature. You probably know that ethanol is a form of alcohol, and our guess is that you have seen alcohol burn at some point. When it is burned, it gives off almost no form of visible smoke. When gasoline burns, there is a dark haze emitted by the burning fuel. A wider use of E15 will help in lowering emissions from cars that lead to pollution. Increasing the concentration of ethanol in gasoline reduces carbon emissions and displaces some of the most toxic and carcinogenic fuel additives.

5. I get a check-engine light when I use E15 in my car but not when I use premium. Why does the fuel cause this?

It’s not the fuel. The minor difference between ethanol and non-ethanol fuel is referred to as fuel trims (how much air and fuel are mixed together by the computer to make the engine run its best), and it is not enough to cause a check-engine light. However, if the vehicle is in a poor state of tune and likely already not as fuel efficient as possible, then that slight difference may cause a light and indicate it’s time for some love for your car in the form of a tune-up or other repairs to get its efficiency back to par.

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.




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