Does gas brand affect you guys' miles per gallon?

[CrazyFukr2k3]

I have a 1991 Acura Integra GS with intake and exhaust.
When it was stock, driving on the freeway, with only me in the car, with the AC off I got 36 miles per gallon (no joke). With AC on and a passenger on the freeway i got 34 miles to the gallon. After I added the intake I dropped to 33, after the exhaust I dropped to 25 (then i used fuel injector cleaner and went back up to 31). Back when the car was stock i could get any brand of gas in the world (even crap AM/PM gas) and i would get 36 on the freeway. Now after the intake and exhaust I noticed that if I fill up with no-name gas from scummy stations locally owned like GasMart or FoodMart (anything with MART on it pretty much) i get horrible gas mileage (like 20). If I fill up with Shell or Chevron I get 31. If i fill up with anything else but that (even the renouned 76) i get low 20s for miles per gallon.

[Vtec]

shell,chevron those types of gas stations use a cleaner gas and have better octane which means better mileage. I went through similar problems with using cheap crappy gas and once I started using chevron and found out that there gas is cleaner etc. i got my mileage back. As for loosing mileage with your intake and exhaust I'm not positive but I seem to remeber ppl saying they got worse mielage with them due to the fact that it breathes more allowing more fuel to pass through. I'm not sure about that tho.

[VTEC_hawk]

have you replaced your fuel filter in a while? if you don't remember or you haven't yet - do so. That should fix the problem - you probably have old junk gas stuck in the filter.

-Good Luck :sun:

[91civicDXdude]

and have better octane which means better mileage

octane has nothing to do with gas mileage. octane is the anti-knock property.

[Vtec]

Originally posted by 91civicDXdude
octane has nothing to do with gas mileage. octane is the anti-knock property.

I'm to hungover to even write how it works. Blah

[NSX]

I think higher octane is better for emissions; b/c higher octane means better combusion-->more combustion-->less waste [ie. nitrous oxides, carbon monoxide, etc.]

[CrazyFukr2k3]

yea i see what you mean by the cleaner gas thing, but isnt 76 good gas? with that i get horrible mileage, like as bad as AM/PM gas (low 20s)

[NSX]

76?
Isn't that low?
Well, I use 80s in my Civic; that's fine.

[b16a3sol]

Originally posted by 91civicDXdude
octane has nothing to do with gas mileage. octane is the anti-knock property.

correct.

there are lot more molecules involved with gasoline than octane, which affect how well your car runs. almost all companies put some kind of detergent into the gas to help keep the motor running well, but chevron and shell are better at finding good ones. back when i had my accord, am/pm gas would not only lower my mileage, but also the responsiveness of my car. this is due to the fact that the shitty am/pm gas didnt help get rid of itself with good detergents. chevron makes my car run a lot better, which is work the extra 5 cents a gallon to me.

the intake and exhaust are going to drop mileage, becuase you are allowing more air into the combustion chamber. in order for stoichiometry to work its magic, you need more fuel to balance the extra air, so you can feel more power.

if you know what gas makes your car run poor, and what makes it run well, why not just use what works best?

[CrazyFukr2k3]

no... 76
the brand 76
the big blue circle with orange "76" in the middle... "official gas of nascar"

[98gsr]

i use 93 super unleaded for my gsr and it brings good milage also

[CrazyFukr2k3]

where do you get 93 super unleaded? highest we have around here is 91

[98gsr]

i don't know if they got 93 in the area where you lived but here in wisconsin they got 93 super unleaded so that's what i used all the time for my car.

[b16a3sol]

the 91 octane gas has not made it past the midwest yet, but its getting there. those of us on the west coast have been enduring it for over a year now, and its only a matter of time before the whole nation is suffering like us. stupid california is the only reason we have to switch anyways, along with lazy gas companies...