Regular versus Premium fuel......
Thread Starter
Burning Brakes
Joined: Mar 2008
Posts: 969
Likes: 39
From: Northern VA
Regular versus Premium fuel......
Is Premium fuel a must or a just a good practice with C5s ? I dont have an owners manual yet.
I think I will always put in 91, but I want to know if Corvettes are set up to operate on 87 OCTANE.
I think I will always put in 91, but I want to know if Corvettes are set up to operate on 87 OCTANE.
Race Director
Joined: Aug 2003
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From: "It's 106 miles to Chicago, we've got a full tank of gas, half a pack of cigarettes, it's dark, and
St. Jude Donor '03-'04-'05-'06-'07-'08-'09-'10-'11-'12-'13-'14-'15-'16-'17-‘18-'19
NCM Sinkhole Donor
It will run on 87 octane - but the owner's manual states that Premium Fuel of at least 91 octane is required.
I'm quite sure if you do a search on "octane" in C5 General, you'll encounter at least one or two threads on this subject.....
I'm quite sure if you do a search on "octane" in C5 General, you'll encounter at least one or two threads on this subject.....
Melting Slicks
Joined: Oct 2006
Posts: 3,447
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From: Los Angeles
/thread
Administrator
Joined: Jun 2007
Posts: 66,409
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From: Bel Air (by way of Fort Worth, TX) Maryland
St. Jude Donor '12 thru '21
91 is the recommended octane level. You can use 87 if nothing else is available but your PCM will pull timing in order to keep the engine from knocking (not good). Use 91 or higher for best performance
Drifting
Joined: Mar 2005
Posts: 1,336
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From: North Canton OH
Engine will still knock. The PCM will adjust when it hears knock, but it will keep attempting to return to normal, thus always getting some knock.
I don't know about you, but I'd pretty much want to avoid *ANY* knock if I could. And you can for $.20-.25/gallon or only 5-6% more $ than 87 octane.
In case you don't know... knock is detonation. Detonation occurs from fuel spontaneously combusting under heat & pressure over time because it can no longer resist the temptation to ignite. Octane is the measurement of a fuels ability to resist combustion. Higher is better.
The knock you "hear" is the random flamefront colliding with the flamefront from your spark. Any detonating could cause craters in your pistons.
I don't know about you, but I'd pretty much want to avoid *ANY* knock if I could. And you can for $.20-.25/gallon or only 5-6% more $ than 87 octane.
In case you don't know... knock is detonation. Detonation occurs from fuel spontaneously combusting under heat & pressure over time because it can no longer resist the temptation to ignite. Octane is the measurement of a fuels ability to resist combustion. Higher is better.
The knock you "hear" is the random flamefront colliding with the flamefront from your spark. Any detonating could cause craters in your pistons.
Safety Car
Joined: Sep 2007
Posts: 3,816
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From: Anchorage Alaska
St. Jude Donor '08-'09-'10
I've always wanted to use that one!
But seriously though... you COULD use 87... but it's not really doing the car any favors, and as was said above, you do get denotation, although briefly. You need to have it happen before the PCM can detect it and apply the correction.
I'd only buy it as a last resort, like as in, the station sold out of premium and you don't have enough gas to run up the road to the next station. Then I'd buy just enough to get to the next station.
It costs about $3 per tank to fill 'er up with premium over regular... Why even consider it?
Race Director
Joined: May 2001
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From: Guelph, Ontario
Let's put this another way, my car when it still had the factory stock tuning would get a couple of degrees of knock retard in the higher gears on a hot day at full throttle even with 94 octane!!
Don't risk it, put nothing but premium in these cars.
Tech Contributor
Joined: Dec 2003
Posts: 19,384
Likes: 87
From: Horncastle Lincolnshire, England
2023 C5 of the Year Finalist - Unmodified
Thats the best series of answers I've seen on this question for a long time and its only post #7. We can lock this one down now
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Tech Contributor
Joined: Dec 2003
Posts: 19,384
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From: Horncastle Lincolnshire, England
2023 C5 of the Year Finalist - Unmodified
And it's after the event so the knock sensors are compensating. Best buy the better gas
Advanced
Joined: Mar 2008
Posts: 60
Likes: 6
From: Cleveland OH
Great thread of advise. I would never consider putting something less in the vette unless absolutely had to - then just a 1/4 tank to get me to the next station. Great advise to show to the wife so she knows I am not just being ****.
