What octane gas is best for my GT-S???

[1986_Celica_GTS]

Hey I'm just wondering if I should be using regular (87 octane), mid-grade (89 octane) or premium (92 or 93) gasoline in my 1986 Celica GT-S?

[91 Celica St]

theres no need to run any more than 87 octane with your celica, you wont get any more power iwhtout tuning from 93 octane on a stock car

[1986_Celica_GTS]

I was thinking more in how well the vehicle runs (quality). What I'm wondering is if my engine is meant to run at a high octane level, med, or low? Premium gas does not produce more energy than regular or mid-grade fuel. Premium gas can be bad for your engine if it was not designed to run at a high octane level. So I need to know what the manufacturer suggests for this model.

Because my engine is the upgrade model for the 86 celica it has the dual overhead cams. Therefore that makes it a higher compression engine correct? It's basically pumping twice as much air through the intake valve right? High compression engines require a fuel that burns efficiently at a higher temperature. That’s what premium fuel does, it burns hot under high compression.

So my main q: IS MY ENGINE A HIGHER COMPRESSION ENGINE? IF YES, IS IT HIGH ENOUGH THAT IT IS SUITABLE FOR THE HIGHER OCTANE LEVEL?

[jaybratt]

I have a 91 gt that I have found runs best on plus, 89 octane. It is noticeably different between that and regular, 87. There is no difference between plus and premium though. More importantly you need to find gas that has little or no alcohol in it. Alcohol makes the car run slow and the gas run out faster. All these people are so into CHEAP gas at am-pm or arco, but the alcohol content is so much higher than chevron, that chevron gas actually ends up cheaper in the long run. To figure it out fill your car at the same place about three of four times and calculate average mpg. Then try another and another. I have found that chevron or shell have worked the best.

[86celica_gt]

I'll try that. I find chevron to be the best too. Thanks for the reply man

[barkroc2]

now dont get me wrong...i agree some gas is better than others, but if your car runs noticably better on 89 than 87.. it shouldn't and theres something wrong somewhere causing that. i run the cheapest shit i can find (except atlantic) w/ no problems to speak of as yet

[jaybratt]

The car gets better gas mileage. I doubt that is a bad thing. With regular it just doesn't seem so smooth as it does with plus.

[91 Celica St]

okay im speaking from pure knowldege here, my pops pretty muych runs a refinery, he bledns tha gas and shit...withought tuning there is NO WAY your car can get more power from diffrent octane, the only thing it may do is reduce pinging/knock

your comp ratio is low its 9.5:1

and i dont know if most of you are aware but arco gas is the exact same thing as chevron gas, arco gets their gas from the chevron refinery, they just do diffrent additives...usa gas and some other gas are bought from shell too, but they add diffrent additives too

to be honest its all preferences, if your car was made form the factory, and the ecu was tuned a scertain way, thats the way it was meant to be, short of a pigy back theres no way yhour gunna change it