I'm a brand new C5 Corvette owner, and I thought I'd post a question for your opinions or knowledge on this topic: what octane fuel is best to use for various reasons? Obviously premium octane fuel will perform better, but what about engine endurance, mileage, etc.? Is there any reason to not use high octane? Is using low octane bad for a Corvette in any way (I accidentally filled up with standard octane, and it runs fine but with a little less "zip").

 

Im a 93 user

 

The owners book suggests 91 and says you can use lower but you will lose a bit of performance. You didn't fill out your profile, It would help to know where you are located because the elevation has a lot to do with octaine, The higher up you are the less chance of knock. Sea level look out.....
I am at 4500 feet and still use 91 because of my tune and timming change.

 

Only 93...... and more times than not I go to the nicer stations in town. Shell, Chevron, and on base. Places that have a high turn around on fuel.

 

I agree

 

91 is the highest here. It is designed for premium so I will use premium. If you put in regular for whatever reason, the timing will adjust and you'll loose some performance, it won't hurt anything. I wouldn't bury the throttle to floor too often without premium though.

I put regular in cars that were designed for it... like my Mazda beater.

 

I use only 87 fuel... I do notice a little pinging at times but when I do I just back off... I'm not into using all that horsepower out front... I just enjoy cruising..

 

Check your owners manual

 

I dont run anything under 93. I was talking to Jeff Creech (a local tuner that knows his s*#t) the other day while he was tuning my car and he started talking about octane levels. He was telling me that he has tuned corvettes to run on 89, but they lost around 30-40 rwhp. He said that with a right tune lower octane levels are okay, but not without it. Hope that helps.

Tyler

 

Thanks for all the replies!

I'm at ~1800 feet right now, but later this year will be moving to the bay area, or ~100 feet.

Ok, so I won't worry about it too much for now, and just fill it up with premium in the future. Also, I hope I'm not being annoyingly ignorant, but what would happen if you did give it too much gas too much without premium?

I did, I guess what I was wondering about was whether it's better at all for the engine to run on a lower octane, or if it's bad in any way, since I accidentally filled it with standard.

 

91 is all we can get around here!

 

You might get some pinging with low octane. An owner of a LS1 SS Camaro told me he gets pinging if he doesn't use high octane fuel.
I put in Chevron 94 or Chevron 92 (don't notice a difference between the two...I guess if I advance the timing with a tune, the 94 will be better). I wouldn't go below 91!

 

Other than a track, where else can you buy high octane fuel? Airport?

Also I use 93 all the time. For me even if I drive normal I still hear a pinging with low grade fuel.

 

This subject comes up often and always generates a heated debate.

The owners Manual actually says:

“Fuel - Gasoline Octane

Use premium unleaded gasoline with a posted octane of 91 or higher for best performance. You may also use middle grade or regular unleaded gasoline rated at 87 octane or higher, but your vehicle’s acceleration may be slightly reduced. If the octane is less than 87, you may get a heavy knocking noise when you drive. If it is bad enough, it can damage your engine.”

E-T, who was involved in the design of the C5, will post long explanations of why the high compression of the LS1 (the LS1 has 10.1:1 compression ratio and the LS6 10.5:1) needs good gas. His advice is 91 minimum and 93 if you can get it. It has a knock sensor which automatically retards the ignition if it senses knock. If its doing that, by definition you have less power and lower fuel efficiency.

In my book, although the knock sensor may protect the engine to a certain degree, it’s still a compensatory adjustment. In other words it’s solving the problem after the event so some damage could occur however slight.

For a couple of cents a gallon, I wouldn't take the chance. JMHO

In UK Regular gas is 95 octane (RON) which equates to 91 octane in the US. The Super Unleaded is 98 octane which is about 93/94. I use the Super when I can get it but not all gas stations sell it here. I pay way more for gas over US prices so its even more of a decision to buy higher octane.

 

I run Premium fuel (Shell or Sunoco) in all my vehicles.
The C-5, the Silverado, the Tahoe and the Harley.
Better fuel, better detonation, better performance. For the little extra money it's worth it.

 

If you are out for a Sunday drive and not geting on it at all, then you can get away with regular gasoline.

 

I did a little experimenting with 93 and 87 octane. Although I did not notice a big difference in performance, the fuel milage was about 2 mpg less with the 87. Calculated out based on price difference, it was actually a little cheaper in the long run to use the 93 -

 

I only use 93 octane.

 

Pinging is bad even a little, it leads to burning holes in the pistons. Look up detonation once.

Being cheap will cost you a new engine!

http://en.wikipedia.org/wiki/Engine_knocking

 

Most of the high octane gas in southern California is in the 91 octane range. If you look at your timing tables for high and low octane gas, low octane has about 12-17% less spark in your cruising area.