Kensmith

91 octane is the best I can find in N. Cali. You guys with limited octane run octane boost? Or just hope it never pings on 91?

wirebender

Running 89 here in texas/ no problems so far in a 2011 gs. 18 or so in town.

NYC6

The Corvette leaves the factory with a tune safe for 91 as some states dont have 93. 89 oct, on the other hand is not a good idea.

keyplyr

That's all I use - Chevron Supreme 91. What's the problem?

You use the octane rating that the car is tuned for. Higher octane is *not* better. There are numerous threads on this topic. Do some reading

StanNH

Why? Shouldn't the computer simply retard the timing slightly?

Raazor

91 was fine for mine prior to the mods.

Now with turbos I still use 91 and still no problems.

91 is just fine.

KenHorse

The Vette's computer will adjust the timing as necessary to prevent detonation.

No worries, even with 89...

casting kid

91 is fine in socal

BadAV

My LS2 runs perfectly fine on 89 octane. I assume it's running on the low octane table but it runs fine for DD.

Since the LS3 has a slightly higher compression ratio it might be more prone to spark knock on 89 octane but I suspect, based on looking at the timing differences between the high and low octane tables, that it would be fine. 91 should be fine for the LS3.

cmonkey713

91 is just about the only choice that you have in a premium fuel in Oklahoma. There a couple of stations in the OKC area with 93 and 100 but you are going to pay through the nose. The LSX motors seem to do fine on 91.

topper7788

Run my 2010 and my past 2007 and 2004 all on regular... No issues...

Don't sweat it....

cclive

Have you ever heard it ping on 91?

SpryGeezer

12K on an '07 coupe in ABQ @ 5K elev on nothing but 91 Chevron or Shell.

speedlink

That's ok. It's tuned for 91 octane. 93 is ok also. More than that is a waste. Also, the computer will pull timing so the ping will not be audible if you use 87 octane, although not recommended. For a short time it's ok.

JoesC5

That is correct for the LS3 engine, but not the LS7 or the LS9. You can only use 89 in the LS7/9 in an emergency, as long as you don't hammer it. As soon as possible, after putting 87 or 89 in the tank, you should get 91(or better yet 93, as that is what GM recommends for the LS7/LS9). The LS7/LS9 is not tuned to run on a steady diet of 87 or 89, like the LS3 is.

Racer

I have a 750 hp ZR1, it runs on 91 and runs well...I think your just fine.

Rossi6998

Ditto...

LDB

Octane requirement is a function of compression ratio and several other smaller things like combustion chamber design. Once those are set, there is an optimum spark advance curve. You lose power if you either retard or advance the spark relative to that optimum. Retarding also reduces octane requirement, so the knock sensors control knock with low octane fuel by retarding the spark, thus losing some power. But the process does not work in reverse, namely, you do not gain extra power by advancing spark beyond optimum. With the Vette engines, 91 octane was the design point and should get you to the optimum advance curve, so octane over 91 has only two very small potential benefits. First, there are always small variations from engine to engine and from fuel to fuel, so you have a bit more wiggle room to be sure you can stay on optimum advance curve. Second, as engines age, particularly if you use cheap fuel which leaves more deposits in the engine, octane requirement increases slightly, so using 92 or 93 octane gives you a bit of wiggle room on that factor. But by the time you get to 93, you are well past the point of any conceivable benefit even from those factors, so octane over 93 is utterly worthless unless you have modified your engine’s compression ratio or camshaft, or have added a supercharger without reducing compression ratio. So bottom line, don’t worry in the least about using 91. It is the car’s design point. Going from there to 93 is somewhere between worthless and a teeny benefit, depending on your exact situation. Going over 93 is utterly worthless under any conditions unless you made the engine mods mentioned above.

Kensmith

I use only Chevron 91 octane in my 65 coupe with a 383 stroker motor. Never used anything but Chevron in any of my vehicles. I'll be picking up my 2005 vert that is supercharged soon so I want to make sure I run the best gas in it. So I will stay with Chevron 91. Thanks!

Landru

Running ethanol-free 91 octane where I live in WI in my Z06.
No problem(s) whatsoever.