Can I/ Should I use E85 in my car that says it can use 10% ethanol?

[lewdwig]

My last fill up of E10 (about 10 gallons) and subsequent additions of regular unleaded (about 5 1/2 gallons) gave me 28.30 MPG in the Saturn; just filled up again with E21.25.

 

[lewdwig]

I filled my car again with 25% E85 and 75% 87 octane and got 31.38 MPG, working some long hours, so almost all back and forth to work. My previous fill of regular unleaded was 28.30 MPG. The weather is warming up and I changed my oil (to RLI 5W-30) and ran 174 miles of the E21.25 with fresh oil.

 

[swalve]

Originally Posted By: cowpie1
My wife used to have a 2002 Chevy Cavalier that was not a FFV. Just for grins, we loaded it up with E85. The check light came on about 30 miles down the road. Ran good though.

The problem is the programming for the ECU regarding the oxygen sensors. Running E85 causes the ECU to go crazy. A overfueling/underfueling condition would probably be the result and therefore cause mechanical problems. The addtional sensors and programming put in the FFV eliminate the problem. It senses the ethanol level in the fuel and compensates accordingly.

Now that being said.... I had a '98 Chevy P/u with the 454 V8 and I could put E85 in it and it would run great all day long without a CEL or problem. I actually ran it for some time with about E50 (mixing levels of E85 and E10 fuels). Got decent mileage and good performance.


I did the same thing in my Grand Prix. The check engine light took a few days to go on. But the car ran fine, if not better. Chances are good it was a "long term fuel trim" error.

I don't see why cars that aren't harmed by 10% ethanol will suddenly be harmed by 85%.

I'm planning on firing up the Dodge Spirit with E85 and seeing what it does with its older computer system.