One of the stations near me started selling E15. If I googled correctly E15 has an octane rating of 92.6. Is there a down side to running E15 instead of 91 E0 with my 91 octane perf/tow tune.

 

Out of curiousity, what is your location?

 

SW Missouri.

 

Downside would be mileage, unnoticeable HP diff (unlike E85 which Turbo vehicles love, if compatable). It comes down to how much cheaper vs 91 vs gas mileage loss.

 

Yeah, that is what I was thinking. I am pulling a pretty steady 19.5mpg right now with the 91 E0 but I am also paying ~2.50 a gallon for it where the E15 is ~1.85

I think I will try a tank out and see what it does. I usually run through a whole tank of gas a week so it won't take long to see.

 

Need to follow this thread... some of our local Sheetz stations have started selling E15. Honestly didn't pay attention to the octane rating. But, it is a mystery what the E content is in our regular unleaded other than it "may contain up to 15% ethanol".

 

I filled up with E15 this weekend. I had 106 miles to empty of 91 E0 left so it won't be 100% percent E15 but I figure it's close enough to see how will act. This is my last tank of 91 E0.

 

It is pretty easy to calculate how much mileage you're going to lose. Ethanol is about 66% the energy of gas so .15*.33 means you lose about 5% of the gallon's energy. So if E15 is more than 5% cheaper than E0, play ball.

As a side not are you sure you're not putting in E10? Short of special pumps at certain stations almost all gas in the US is an E10 blend, even premium. If you are putting in E10 and move to E15 your mileage will drop about 2%.

When I lived in MN I had a FF tundra and I'd always check to see what was the better deal E85 or regular by seeing if E85 was 25-30% cheaper or not as E85 is between a 25-30% MPG reduction.

 

Most stations where I live have E10 except for Premium which is E0.

 

I have ran a few tanks of E15 through my truck now with surprisingly no loss in mpg. I will say that it does feel a little lower on power compared to the E0 that I was running but going from $0.15/mile to $0.10/mile it makes it worth it.

Here is the last tank I ran through it along with a picture of the pumps I am using.