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Since E85 gets poorer fuel economy can anyone tell me the magic formula for when it is more economical to purchase E85 instead of 87 octane? Someone told me once that it is a better deal if the E85 can be purchased at 50 cents cheaper than 87 octane? Any suggestions or experience?

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Price varies depending on your area. Up here in NY its like 10 cents cheaper. You lose 2-3 mpg but the trade off in my opinion on my HD I had was a better driving truck. Might have been a placebo effect but sure felt stronger. Plus it smelt awesome LOL. I ran it spring/summer/fall in my HD truck and went to 87 for the winter.

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I've run it before in other vehicles and did not notice a power increase at all. I did notice a MPG decrease though. I was curious when other people make the decision to purchase E85 or 87. Do you just buy it all the time during spring/summer/fall or when the price is at a certain point?

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Depending where you get information, it seems that running E85 gives you 20-30% worse fuel economy per gallon.

 

So to justify that you would have to buy it for the same discount. At today's price in my town that would be .45 - .67 cents per gallon.

 

So I would tend to agree with your friend that says you need to get it for at least 50 cents/ gallon less, otherwise you're just burning money.

 

I don't even know if my truck can burn E85. I know there's no "Flex Fuel" decal on the tailgate. I'm going to continue buying the regular gasoline with 10% ethanol blend they give me at every gas station.

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In short, there's never a good reason to run it. It's normally used for big fleets. Companies that have a bunch of vehicles that don't drive long distances that don't want to buy higher priced fuel. Most of them actually have their own filling stations.

 

 

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Posted (edited)

SAE dyno charts from GM show 20-25hp and around 50 ft.lbs torque on the 5.3 for 2014+ E85 capable trucks. I would imagine those increases would be felt as those are near a dyno tune result. Just from switching fuels. Remember, these are direct injected and run 11.0 to 1 compression ratio.

 

The older engines picked up like 5-10hp and 15 torque which really would not be noticed that much if any.

 

Also, have a read on this link https://ls1tech.com/forums/fueling-injection/1561739-e85-subsidies-whats-everyone-s-thought.html#post16478331 check out post #6.

 

Depending where you get information, it seems that running E85 gives you 20-30% worse fuel economy per gallon.

 

So to justify that you would have to buy it for the same discount. At today's price in my town that would be .45 - .67 cents per gallon.

 

So I would tend to agree with your friend that says you need to get it for at least 50 cents/ gallon less, otherwise you're just burning money.

 

I don't even know if my truck can burn E85. I know there's no "Flex Fuel" decal on the tailgate. I'm going to continue buying the regular gasoline with 10% ethanol blend they give me at every gas station.

 

Yellow gas cap and a sticker on the lower corner driver's window on 2013-2016 trucks. 2017 its only the sticker on the window because of the capless fuel fill.

Edited by 15HDriver

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Correct mine has a yellow cap and says E85. Thanks for the info guys!

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I've been experimenting with E15 the past 4 tanks. I've been getting the same mpgs as 87 octane which is E10; however E15 is 10-15 cents cheaper per galon and comes in at 89 octane which isna steal because 89 octane here runs 30 cents more than 87.

 

As for E85, i ran that 3 years ago and the calculus i came to was that at a minimum E85 needed to be at least 25% cheaper in price than 87 to be comparable to 87.

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The only reason I would use E85 is maybe if I wanted a little more HP and TQ to help with hauling or towing. E85 just needs more of it to burn so it will always give worse MPGs. But, that's a small price to pay if you want that extra performance. Also as others have said, just to use E85 for normal driving it would only make sense if it's way cheaper than 87.

 

I had my '14 for 2 years and never was able to try E85 because there's not any stations that I could find in my area that sells E85. I believe I would have had to drive over an hour to get it so it would be only if I was in that area anyways. I know there seems to be more and more stations selling none ethanol which I read is better for the engine. Not sure if it helps anything, I think it just burns cleaner than if it had ethanol in it.

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When I had my 14 GMC the talk on this site was the engine ping on anything less than mid grade fuel. E-85 was easy available in my area and much cheaper than mid grade gas. It didn't take long to feel the difference in performance, so it became my primary fuel.

 

 

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I don't even know if my truck can burn E85. I know there's no "Flex Fuel" decal on the tailgate. I'm going to continue buying the regular gasoline with 10% ethanol blend they give me at every gas station.

 

At least for GM, yellow gas cap means E85 compatible.

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I prefer to run E85 in my truck in order to get the horsepower boost from 355 to 380, especially when towing my travel trailer. It also runs cooler and cleaner than gasoline, and pollutes the air less than gasoline.

 

Therefore, when I can find E85 at 75-80% of the price of regular gas, I buy it. The closest E85 that is priced right is about 55 miles from where I live. Therefore, I fill up 5 gallon gas cans with E85 to put in my tank at home or when I can't find E85 at a good price.

 

E85 has an octane rating of more than 100. Our Flex Fuel Silverado's have a sensor that detects the octane rating of the fuel and advances the timing when high octane fuel is detected, providing more power.

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Posted (edited)

On long island ny, i have 3 stations for e85. I have a 14 1500 and a 15 suburban. Both cars run e85 all the time. 1.55 gallon vs 2.39 a gallon 87 2.55 for 89. Just did a trip up to lake george in the burb. Fully loaded kids and gear was prob close to 1500lbs. At 70mph my mpg was 17 and change. My wife driving in the street the burb sees 11. She has a heavy foot. My silverado, 80% city driving loaded with material 75% of the time 12 and change mpg.

 

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Edited by cmysstailights

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I wish I could find it around here for even 25 cents less than 87...

 

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Great info guys! I didn't think about using E85 when towing. I'll start experimenting with it. I have a few gas stations near my house that sell it. Would anyone buy E85 if it was the same price at 87 octane if you're about to tow a camper a long distance?

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