Ive been told many diffrent things about what is the best gas to put in to my 88GTU.
The owner before me told me only to put in permium so thats what ive been doing. But i have heard from others that the lower grades will make the car run better.
So what is the real deal?

 

your car was built for 87 octane

 

only put in the cheap stuff. lower octane burns better. higher octane is an unnecesary waste in a non-turbo car. your car will run better as well.

 

87 octane "Regular," nothing else.

 

Thanks. I wonder why the pervious owner told me wrong?

 

i dunno the theory behind this (cuz im too lazy to go find out) but apparently the 787b mazda lemans car used 83 octane gas??? not sure if this is true but i do run 87 octane now. except when i am on the racetrack, i use 94 cuz im stubborn:P

 

Yes N/As love lower octane. You can put in the higher octaine but it's a waste of money.

 

87 or lower if I can find it.

 

hmmm......I have a 1987 Gxl & i use 93 octane. Its the N/A motor but i smacked a turbo on it. So should I stay at 93 or go back down to 87.

 

Two reasons I can think of:
1) The engine is badly out of tune and/or worn, and the higher octane fuel acts as a band-aid.
2) The previous owner was under the common misconception that high octane fuel has better detergents and more power than lower octane. (According to current knowledge, the new Shell V-Power premium really does clean better than the lower grades of gasoline, but this is the exception).

 

plus the higher octane is still burning when it goes in to the exaughts there for burning up your exaughst that can get price

 

93 at least

 

Since the motor was built for 87 octane.. should i go with 88 since 87's not available here? Regular gas out here is 86 octane.. Plus is 88, and Premium is 91.

 

thanks

 

i ran 86 all the time.. motor is still going strong with 150k+ miles...

im gettin another 7.. it'll get 86 also. But i make sure i get good quality 86.. I get gas at sunoco

 

can anyone decipher this?

 

i think what he's trying to say is.....deep breath..... "the higher octane fuel doesn't completely burn or burn fast enough to finish burning when the exhaust port opens, this burning fuel in the exhaust system can lead to catalytic converter failure which can get pricey".....?

 

I use 87.I used to use 93 a few years ago.Couln't tell a bit of difference when I switched so I run the cheap stuff.I beleive the reason n/a rotories like low octane is the long narrow combustion chamber.This causes the flame front to want to extinghish before it travels the full length of the chamber.This is why we have trailing plugs to ignite any unburnt mixture. Since the lower octane ignites easier it burns faster or more completly before it is spit out the exhaust.With turbos you have to run 93 or better because the boost provided by the turbo also makes the mixture more prone pre-ignite(knock) which is bad.I think I'm pretty close here feel free to correct me where I'm off.

 

Pretty close, although the reasoning behind running low octane on an N/A is not solely becasue of the design of the combustion chamber.

As a rule of thumb, you want to run the lowest octane you can SAFELY burn. This yeilds the most power.

For boosted applications (stock TII), you need to run high octane for added knock protection. Once the mods start going in, your octane requirements will vary.