BlackandTan2004

I got a place close by my house that sells 93 octane @10% ethanol. I got another place also close by that sells 91.5 octane ethanol free.... For those of you who know a whole lot more about fuel & ethanol what would you recommend?

I have only ever put the 93 in the car..... Any benefit to running 91.5 ethanol free. Car isn't raced, occasional spirited driving.

73Corvette

JMHO... I would go with the 91 NO ETHANOL

That's what i get at home ALL the time... when on trips however sometimes finding NON Ethanol is not possible... almost every time at some point we have the gas gauge issues... till I either put in some Techron or we get home to good gas...

ramm21

There was a thread not even a few weeks ago that dealt with the same question. You will get a lot of polarized opinions.
I'm in the opposite corner of 73Corvette.. I think people are scared of ethanol because of so much misinformation. They tell you it will grenade your motor over time, plug up your injectors, ect...
The way I look at it, if people on this forum have been running 10-15% ethanol fuel with no problems for years, I wouldn't worry about it.

73Corvette

I have no fear of it hurting my car, I just have experienced on several occasions that is does jack with my gas gauge (ethanol fuel) my car was tuned for 91...so I try to stay as close to that I as I can... sometimes the ethanol fuel is the only thing available and I'm not afraid to use it, I just expect gas gauge issues...and the Techron always fixes it.

I take that back... I do have a concern with Ethanol fuel and my 02 sensors and Catalytic Converter...I still don't think it will make my motor explode or plug injectors...although our turbo 87 4runner DID NOT like ethanol... at ALL.

http://fuelschool.blogspot.com/2009/...catalytic.html

neutron82

is the car stock, modified, any tuning work done?... there is probably no benefit of having less octane in this case... to a point, the more octane available the more buffer zone you have to prevent detonation... now if you car was stock on the stock tune and you were trying to choose between race gas and 93 pump then yeah, having less octane in the 93 pump will benefit you more... I wouldn't run anything less than 93 in my car personally unless it just wasn't available and ethanol is not a bad thing, the only negative I can think of is less fuel mileage but with such a small percentage being used it will most likely go unnoticed

ramm21

Thanks for that link. I haven't run across the O2 sensor issue all that much, but it makes sense that ethanol gets into motor oil, then breaks it down. The article talked about adding a cleaner through the fuel system which may help with that build up. I wonder how well that works, since people who care about their cars (like on this forum!) tend to use cleaners much more often than the general public.

Also, do you know why the ethanol is making the gauge wonky? Just from a scientific perspective, if you run two different fuel types they should have different mixes of additives, right? And if so, it wouldn't really be a true ethanol vs non-ethanol test since you have other additives in play?

feeder82

my only concern with ethanol gas is long storage situations. ethanol attracts water.

Rick369

I have the option of 91 octane non-ethanol or 93 octane ethanol. I have used both. I have to drive 6 miles into another county to get the non-ethanol but that would not be an issue. My previously owned 2001 vert and my current 2003 vert both run and perform better with the 93 octane ethanol gas, so that's what I use. I always buy top tier gas. Never had a gas gauge issue with either car.

gimp

Either one will work, however, ethanol-free gas has more power for the volume.

If the octane rating is correct, well, 91.5 is fine to use in a vette. As long as they are rated the same (RON+MON/2, in the US, right?)

runner140*

I use the 93 octane with (up to) 10% ethanol. In south Florida, that's our only option...is with ethanol.

Vetteman Jack

I use 10% ethanol do gas in all my cars and have done so for many years. Not had any problems at all. Just my experience.

BlackandTan2004

Thanks for all of the information guys! I will continue to use the 85%/15% 93 blend. But I think when I put the car up for the winter I will fill it up with the ethanol free and seafoam! (Used the blend and seafoam last year).

The car is relatively stock, Vararam, Corsa Sport, Corsa X-Pipe. The car will be tuned late this summer/fall and after that I most likely will not mess with any other performance goodies.

Macleod52

I asked ET this same question last year and he said he'd go with 93 w/ethanol. Sadly I didn't save the conversation so I can't post exactly what he said.

QCVette

Either one should work fine.

If you do not have ping with the ethanol free, that is what I would use. There is more energy in gas than ethanol, so it should make more power and get better mileage unless your car needs more octane.

Either one should work fine, so I would try a couple of tanks of each and compare if you notice any difference or mileage changes.

BlackandTan2004

Speaking of ET, haven't seen any recent contributions from him. I try not to stalk users through their profiles to see their activity though.

Rick369

Where do you live? There are no gas stations in my area that sell 15% blended ethanol. Only 10% max.

BlackandTan2004

South Central PA, just north of the Mason Dixon line. I think it is 10%..... Not 15%. I think I was confusing E85 (100-85=15). I work with numbers all day...... they all begin to run together.

Gordy M

Something to consider, the C5 was developed and all the engine management programming was done in the early to mid 90's. The O2 sensors at the time were specified for the gas that was then available--mainly non-ethonal gas. By 2008 GM realized the ethanol was adversely effecting the O2 sensors and they issues new spec's with a greater resistance to the ethonal additions--including E85. So if you have stock O2's you might want to upgrade to the newer ones, If you still have a choice between straight and ethanol, then it is wise to replace the old Os's.

CactusCat

And its a proven fact, you'll get better gas mileage with 100% gas. I've done it over and over again. My 98, when it was stock, was taken on a trip from OKC to Detroit. I had used nothing in it but 100% gas. I filled up and started driving to Detroit. I stopped in Rolla, Mo and filled up and I got 29.5 MPG. The rest of the trip was 93 octane 10% ethanol gas. The next fillup was 27.5MPG (there was still ¼ tank left of the 100% gas when I filled up) and then the rest of the trip I averaged 27MPG. 10% ethanol = 10% less mileage. I've proven that same fact several times in my previous work car, an SUV. Performance was noticeably less on the 10% ethanol gas as well. Like 73Corvette said, it's what your car is tuned for. Since the OP has both 100% and 10% ethanol gas available to him, why not try it our for yourself and see if you can tell the difference in gas mileage and performance?

Joshboody

From engine performance, E10 93 is better. Only neg I can think of is sitting for long periods and water absorption.

FYI: I switch back and forth from E10 91 and E48 (half and half), mostly for increased summer time performance (live in hot AZ). I love the ethanol and noticed NO negs.