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Coach & Powertrain: Mixing Ethanol and Gasoline

Originally Published in MotorHome Magazine

We own a 2005 National Dolphin with a Workhorse chassis. At this time, I am looking at major maintenance expenses, which I can cost out, but the unknown factor that you may help me with is the impact E85 gasoline will have on my engine. I have about 33,000 miles on the motorhome and I generally drive 6,000 miles per year. I have heard some scary stories concerning E85 gasoline. I’m thinking this might be the right time to trade for a diesel model. What do you think the potential for engine damage is when using E85 gasoline?

Charles Tornatore | Jensen Beach, Fla.

I think you are confusing E15, which is gasoline containing 15 percent ethanol, with E85, which is ethanol containing 15 percent gasoline. E85 has existed for a while for use in flex-fuel vehicles only. The EPA recently announced it is planning to introduce E15 for use in certain vehicles that can tolerate it, instead of E10, which is currently in wide use. According to the EPA, both E10 and E15 would be available so that drivers could choose which one they want to use.

Your engine is not a flex-fuel model and therefore is not designed to be able to operate on fuel mixtures varying from 100 percent gasoline to E85. However, your coach is fairly new with a fuel-injected engine and oxygen sensors that provide the computer with feedback information on fuel mixtures. These engines have proven to be quite tolerant of E10 fuel, and might operate satisfactorily on E15 (the jury is still out). So if this is the only reason you are considering a diesel model, you can stop worrying, at least for now.

– Ken Freund

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