use regular gas?

[ALbadboy]

Originally Posted by Leonardo

Premium non-ethanol ONLY!!! It makes a huge difference.

I have a place here that sells 89 no ethanol... Or I can get 93 with... I hate it.

[BuBlake]

I think my car had 87 from the dealership. After my first fuel up, it seemed to wake up the engine a lot. I'm not sure if the reason for poor initial performance was a break-in issue or 87 octane, but it's had nothing but 93 since then and runs great.

Also, after switching to Shell gasoline, the bird chirping under the hood is all but gone, which was a nice surprise.

[RYU]

Using 87 will not destroy your motor or cause it to knock. The manufacturers suggest 91 because it is tuned to the advertised hp/tq/mpg numbers at that octane rating. The factory knock sensors and O2 sensors will tune down your timing and other factors to run on 87. You may not achieve the full 199.9hp on the FA20 but it will not damage your car.

In other words, lower octane will decrease performance but not be detrimental. Would I run it for the long term? No.

[avp1]

Originally Posted by RYU

Using 87 will not destroy your motor or cause it to knock. The manufacturers suggest 91 because it is tuned to the advertised hp/tq/mpg numbers at that octane rating. The factory knock sensors and O2 sensors will tune down your timing and other factors to run on 87. You may not achieve the full 199.9hp on the FA20 but it will not damage your car.

In other words, lower octane will decrease performance but not be detrimental. Would I run it for the long term? No.

If you do not want problems with your engine down the road, do not put anything other than 93 gas in this car. It will probably survives for a year other two on lower octane fuel. But if you plan to keep it longer, follow user's manual, which states 93 only. And pass on any gas with ethanol content over 10%, it is not compatible with FA20 engine either. Welcome to the world of real sport cars, where you need to do something special just to be able to use them daily.

[Bonburner]

Originally Posted by RYU

Using 87 will not destroy your motor or cause it to knock. The manufacturers suggest 91 because it is tuned to the advertised hp/tq/mpg numbers at that octane rating. The factory knock sensors and O2 sensors will tune down your timing and other factors to run on 87. You may not achieve the full 199.9hp on the FA20 but it will not damage your car.

In other words, lower octane will decrease performance but not be detrimental. Would I run it for the long term? No.

Cars that have this sensor actually say in the manuals and some advertisements that one can change octanes, this car does not mention any sensor and advises no less than 91.

[empower-auto]

This car already under-performs on 91 octane fuel. Anything less is seriously risky. With 94 E10 it seems to run fairly well.

[Craig]

Originally Posted by Leonardo

Premium non-ethanol ONLY!!! It makes a huge difference.

Stay away from ethanol, that cherp is rather annoying. Its not too hard in jersey to find 93 w/o ethanol thankfully.

[Turbowned]

Just don't. The engine will pull timing in order to run on it if your only option were to run regular fuel, but you should never do it unless it is a last resort.

[RYU]

Originally Posted by avp1

If you do not want problems with your engine down the road, do not put anything other than 93 gas in this car. It will probably survives for a year other two on lower octane fuel. But if you plan to keep it longer, follow user's manual, which states 93 only. And pass on any gas with ethanol content over 10%, it is not compatible with FA20 engine either. Welcome to the world of real sport cars, where you need to do something special just to be able to use them daily.

Then I guess all of us here in CA are in trouble with our 91 octane gas

Originally Posted by Bonburner

Cars that have this sensor actually say in the manuals and some advertisements that one can change octanes, this car does not mention any sensor and advises no less than 91.

I know what you mean. Lexus is one that advertises using different octanes. Though, just because they don't advertise it it doesn't mean it won't work. Take some time to read up on Long Term Fuel Trims and Short Term Fuel Trims. It might help folks draw their own conclusions.

Again, would I do it? No. If it was half the price as 91 I might because i'm not at redline on my commute to work and will not benefit from the added octane as much.

[Leonardo]

Slightly off topic... What is the highest octane fuel you can benefit from on a stock tune?

[DarkSunrise]

I'd be surprised if a high compression engine such as the FA20 didn't have a knock sensor. So the risk of damage to the engine from detonation is probably slim.

Still, it's obviously not good for the engine in the long-run and you'll get worse gas mileage with the lower octane fuel.

[avp1]

Originally Posted by RYU

Then I guess all of us here in CA are in trouble with our 91 octane gas

Yes you are.

[Tt3Sheppard]

I feel like i get worse mpg just using fuel with 10% ethanol in it :|

[CrazyWookiee]

You do. I kept track of how much I got out of each tank. Shell 91 Ethanol free gives me between 7-10% better mileage than 94 10% Ethanol. But 94 definitely feels snappier and I get better throttle response.

Originally Posted by Tt3Sheppard

I feel like i get worse mpg just using fuel with 10% ethanol in it :|