Anyone Use E15 / 15% Ethonol in their 5.3L Engine?

[Micahsd]

I was just curious if anyone has regularly put E15 gas in their gas tank and what their experience was? I know the manual says it's fine up to E15 or 15% Ethonol. I've got the 5.3L engine which doesn't require premium gas.

I live in Iowa and the E10 (87 octane) is discounted as an incentive to promote ethanol. The local station has E15 (88 octane) discounted a little further about at around.15 cents cheaper than the regular E10. There currently isn't a big enough cost difference for me to change to E15 all the time, but if there's a large enough difference at all in the future I might consider it.

What I've filled up all my vehicles with for the past 15-20 years is the E10 (87 octane) or whatever the cheapest option is. I'd skip the ethonol entirely, although that's significantly more costly as premium (91 octane) is the only non-ethonol option and that's usually $1-1.50 more expensive. The only time I use Premium is for my lawnmower since it doesn't have Ethonol or back when I had a Corvette which required it (even though sometimes I out the regular E10 in it without any issues).

Back when I had a 2007 Tahoe, it was FlexFuel and could handle E85 (85% ethonol) and the cost per gallon was a lot cheaper back then. I did experiment with running that at that time and my end result was worse gas mileage (in the end the cost difference per gallon made the cheaper option a wash with the regular E10 option). I'd suspect comparing E10 to E15 that I'd probably see the same thing with slightly less gas mileage, but if the price were a lot cheaper maybe it would be worth it???

I hope to not get a debate started on here whether ethonol is good or bad for engines...pretty sure it's not the best thing, but the vehicle is supposedly designed to handle it. Thanks for checking out the post.

 

[swathdiver]

I was just curious if anyone has regularly put E15 gas in their gas tank and what their experience was? I know the manual says it's fine up to E15 or 15% Ethonol. I've got the 5.3L engine which doesn't require premium gas.

I live in Iowa and the E10 (87 octane) is discounted as an incentive to promote ethanol. The local station has E15 (88 octane) discounted a little further about at around.15 cents cheaper than the regular E10. There currently isn't a big enough cost difference for me to change to E15 all the time, but if there's a large enough difference at all in the future I might consider it.

What I've filled up all my vehicles with for the past 15-20 years is the E10 (87 octane) or whatever the cheapest option is. I'd skip the ethonol entirely, although that's significantly more costly as premium (91 octane) is the only non-ethonol option and that's usually $1-1.50 more expensive. The only time I use Premium is for my lawnmower since it doesn't have Ethonol or back when I had a Corvette which required it (even though sometimes I out the regular E10 in it without any issues).

Back when I had a 2007 Tahoe, it was FlexFuel and could handle E85 (85% ethonol) and the cost per gallon was a lot cheaper back then. I did experiment with running that at that time and my end result was worse gas mileage (in the end the cost difference per gallon made the cheaper option a wash with the regular E10 option). I'd suspect comparing E10 to E15 that I'd probably see the same thing with slightly less gas mileage, but if the price were a lot cheaper maybe it would be worth it???

I hope to not get a debate started on here whether ethonol is good or bad for engines...pretty sure it's not the best thing, but the vehicle is supposedly designed to handle it. Thanks for checking out the post.

Different generation and engine, mine gets better mpgs on E15 and E20 than on E0 or E10.

 

[robgreg75]

I have a 2010 that is flex fuel that I did a lot of tuning on myself and finally got it to get decent mileage on E85, the factory tune does not take advantage of the high octane of E85 mine got like 12-13mpg on E85 with the factory tune. I took 3 trips in it last year from DFW to Missouri and only used E85 all 3 trips and average 15mpg not bad at all with the price difference since on gas it doesn't ever seem to get more than 17mpg on the highway.

Haven't tried E15 on my 2021 since most the gas stations I go to don't even have it here.

 

[wsteele]

My Flex Fuel 2007 Yukon runs better on E85 (more like E75 here, when I have tested it) than E10 or Ethanol free. The mileage hit isn't made up for with lower prices as there is a paucity of E85 stations, so the guy that sells it (one here within reasonable driving distance) isn't trying very hard.

My new 6.2L Sierra only gets Premium E10 (generally about E6 when I have tested it) as we don't even have E15 here that I have ever seen.

 

[B-train]

I have a 2010 that is flex fuel that I did a lot of tuning on myself and finally got it to get decent mileage on E85, the factory tune does not take advantage of the high octane of E85 mine got like 12-13mpg on E85 with the factory tune. I took 3 trips in it last year from DFW to Missouri and only used E85 all 3 trips and average 15mpg not bad at all with the price difference since on gas it doesn't ever seem to get more than 17mpg on the highway.

Haven't tried E15 on my 2021 since most the gas stations I go to don't even have it here.

What software did you use for tuning? I have a 2008 and ran E85 as a test. It's not flex fuel - 6.2L. It ran awesome on it though. Got about 13.2 mpg with a combination of city and hwy which stunk. I get around 15-16 (mixed driving) on 87 with 10% ethanol. Up to 20 on hwy.

We recently have gotten E15 around here in WI. So far, I think I prefer it over the E10 for the 6.2L. I haven't run enough tanks back to back to see the real mpg change, if any.

 

[robgreg75]

What software did you use for tuning? I have a 2008 and ran E85 as a test. It's not flex fuel - 6.2L. It ran awesome on it though. Got about 13.2 mpg with a combination of city and hwy which stunk. I get around 15-16 (mixed driving) on 87 with 10% ethanol. Up to 20 on hwy.

We recently have gotten E15 around here in WI. So far, I think I prefer it over the E10 for the 6.2L. I haven't run enough tanks back to back to see the real mpg change, if any.

I used HP Tuners and did a lot of playing with it. If yours is not flex fuel you are running way way lean when you put E85 in. Ethanol is not as energy dense as gas and the engine needs more fuel. With mine I increased the timing significantly when running E85 that is what got the efficiency to reasonable. I just did a road trip and filled up with E85 along the way and it got 16.6 mpg according to the dic on the tank at on the highway.

 

[B-train]

Thanks for the info. Once in saw the CEL, I figured that was the issue. It still ran quite well anyways. What did you end up increasing the timing to? I see 32 to 42 BTC cruising depending on pedal input with 87 fuel

 

[robgreg75]

Thanks for the info. Once in saw the CEL, I figured that was the issue. It still ran quite well anyways. What did you end up increasing the timing to? I see 32 to 42 BTC cruising depending on pedal input with 87 fuel

I haven't touched it in years and the laptop I used that has my program died. I even played with increasing timing using 93 to get better fuel economy, it did improve but not enough to offset the increased cost of 93 vs 87. So I just stick to 87 and E85 when it is not super expensive. Last week I bought E85 for $2.50 a gallon in Waco, TX. With HP tuners you can data log while you drive and watch for any detonation from too much timing, you can see when the computer pulls timing and know to adjust it.