Octane rating. Options

[zakinabox]

i was wondering what people used for gas in their cars octane wise for a 5sfe, ive heard that it really doesnt matter especially with a stock 5s and i noticed a few posts of people saying they use 91 but i assume those were on swaps and cant seem to get to the bottom of this..

what the hell does it matter? lol and what SHOULD i use?

thanks for any input to put my mind to rest =D

[HectortheRican]

For bragging rights, 91+
For financial smartness, regular unleaded.

Unless you've got super high power racing fuel with 100+ octane, it doesn't matter what you pump, there's hardly a difference.

[Johnnyny]

cheap gas is fine

[dudeofchaos]

Shell V-Power or run outta gas, nothing else goes in there.

[4-eyed-freek]

dont you have to use 91 if you advance or retard your timming?

This post has been edited by 4-eyed-freek: Sep 12, 2010 - 11:03 PM

[HectortheRican]

dont you have to use 91 if you advance or retard your timming?

Octane rating is a system used to measure how 'difficult' it is to ignite gasoline. Higher octane rating = harder to ignite. Reason racing fuel has such a high octane rating is because they don't wanna risk the gas igniting when it's not supposed to.

Personally, I only fill up with Chevron premium. Proven results on my dad's 4AGE. 300,000 miles, only Chevron premium.

This post has been edited by HectortheRican: Sep 12, 2010 - 11:10 PM

[monkey_matt]

99+octane, altho that is in the UK, on a Jap import (where the normal is 102 octane iirc)

[b22ri22an]

a stock 5s in the US will run the same on 87 octane as it will on 93 octane the only difference will be how much you pay

[samir0189]

a stock 5s in the US will run the same on 87 octane as it will on 93 octane the only difference will be how much you pay

[richee3]

a stock 5s in the US will run the same on 87 octane as it will on 93 octane the only difference will be how much you pay

x2.

HectortheRican is exactly right. Octane rating is a measure of the detergents used in the fuel. A high compression engine can detonate the fuel when the piston compresses the fuel in the cylinder, BEFORE the spark plug actually ignites. You don't want that to happen. So with a high compression engine/turbo engine, you need a higher octane fuel to ensure that there is no detonation before ignition (knocking.)

With the 5S-FE or 7A-FE, you have an economy engine. Not a high performance engine. You're literally throwing your money away by pumping premium. Your car will run exactly the same on 87 as it will 100+. Thinking that your car has more power or that you are getting better gas mileage simply because you pumped 91 is nothing more than the Placebo effect. However, for those of us with the 3S-GE BEAMS engine or the 3S-GTE, there really is a need to pump 91+. It will resist knocking and avoid costly engine damage.

Not all fuels are equal though- if you have the chance, pump fuel from a top tier station. If there's a no-name gas station on one side of the street selling fuel for $2.75/gal and a Shell on the other side of the street selling the same octane fuel for $2.80/gal, pump the Shell. No questions asked. Top tier fuel truly is better.

Links to read and learn from:
Top Tier Fuels.

Car and Driver- Regular vs. Premium.

[Stambo]

i run 93 but that is because i have a 3sgte

[cyberblader1130]

Im not sure on the octane rating, im guessing its around 91. I only fill up with gas from 2 places. Shell and BP. Reason for this is the fact that around here, their premium gas does NOT have Ethanol. Ive noticed a difference of 2-3 mpg depending on the place i get gas from.