Hey guys, I wanted to talk about a interesting topic that many of you guys may have encountered when filling up.

I have a 2005 G35 Coupe, currently at 162K miles.
Only mods I have: TopSpeed Pro N1 Catback Exhaust.

So, recently I realized in my area 100% gasoline prices are cheaper than let's say 91 octane gas prices mixed with 10% Ethanol.

I did a test once filling up with 91 octane with 10% ethanol, and once with 100% regular gas, as far as mileage from a full tank, I did not see any difference. Both times I tested it on the same route I come and go from.

I could fill up using 91 Octane mixed with 10% Ethanol for prices around $2.30-$2.40 per gallon or I could fill up 100% regular gasoline for around $2.19.
Btw, I live in Atlanta.GA area.

My question is which would be a better option? I do not mind paying more to fill this baby up ,but I do not like putting ethanol in my car.

As far as the health of the car is concerned, do you guys agree filling up 100% regular gas compared to a 10% mix of premium ethanol gas?

Let me here your concerns, and I am sure you guys have had different experiences, I would love to hear them below.

 

I dont think ethanol is great for your engine, but if thats all you got, I wouldnt worry about it. I always put in the lowest octane required. Had an 04' CTS-V a while ago... 87 octane all day!! Still was fast as hell. Maybe lost 5hp, but who cares on the street? I could live with 395hp

 

lol its not about the horsepower loss its about detonation of your motor. there is a reason they recommend premium fuel in higher horsepower cars. but most new cars will adjust the timing if lower octane fuel is used.

but on topic. i would choose 100 gasoline if i had the choice (which i really dont living in socal) cause ethanol absorbs water and your dont get as much power per ounce of ethanol vs per ounce of gasoline.

 

You should get the pure gasoline if you can, especially if it's cheaper. I wish I could get pure gasoline at an everyday accessible pump here in Mass. Ethanol has a lot of negatives as far as potential for increased damage to the fuel system as a result of water contamination (ethanol absorbs water), fuel separation (when the fuel sits for a while in vehicle not used regularly), and corrosion to the fuel system due to the ethanol being an alcohol that doesn't play nicely with various rubbers, plastics, and aluminum parts. Pure gasoline also has a higher stored energy content, but normal street cars won't take advantage of that and there should be no difference in HP or fuel economy output between the two for nearly all road cars.

 

Hey! Fellow Atlanta area G-er here. I'm OTP North.

I've seen this as well. I'd go ethanol free all day BUT I've only seen ethanol free in 89. I buy 93 for the G, and don't believe that the lack of ethanol is worth the risk of detonation personally. If you have ethanol free gas in 91 or above, go for it!