Gasoline
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5th Gear
Joined: Feb 2008
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Gasoline
I'm in California and I've been told that because of environmental laws in my state the gasoline is much higher quality and as a result high performance cars like my 2001 corvette do not need 91 octane. Is that true?
Tech Contributor
Joined: Dec 2003
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From: Horncastle Lincolnshire, England
2023 C5 of the Year Finalist - Unmodified
Stand by for a variety of answers
This subject always generates a lot of 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 an explanation of why the high compression of the LS1 needs good gas (he says 91 minimum and 93 if you could 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 it 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 won'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.
This subject always generates a lot of 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 an explanation of why the high compression of the LS1 needs good gas (he says 91 minimum and 93 if you could 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 it 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 won'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.
Race Director
Joined: Aug 2001
Posts: 10,783
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From: Hurricane Alley
I have to use premium because of the compression that Im running but if you car is stock you can run on regular and middle grade. Personally, Id rather spend the extra $3.00 and get premium, since thats about all you are saving. 
Le Mans Master
Joined: Dec 2000
Posts: 7,096
Likes: 153
From: "Atlanta" Ga.
Stand by for a variety of answers
This subject always generates a lot of 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 an explanation of why the high compression of the LS1 needs good gas (he says 91 minimum and 93 if you could 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 it 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 won'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.
This subject always generates a lot of 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 an explanation of why the high compression of the LS1 needs good gas (he says 91 minimum and 93 if you could 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 it 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 won'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.
Good answer
The person that was telling you this may be confusing Octane ratings with some type of environmentaly friendly thing Ca. may require in the gas to reduce emissions, but 91 octane should be the same in Ca. or Ga.
Team Owner
Joined: Jun 2007
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From: Down the Shore New Jersey, Elev.3 feet
St. Jude Donor '17
I guess its good that I use Shell super 93 huh? 
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From: Southern New Jersey, The wet part at the bottom
St. Jude Donor '08-'09-'10
California gas? 
Gas can vary in quality, but not from what state it's dispensed from. (In less there's a state not blending 10% ethanol)
Gas can vary in quality, but not from what state it's dispensed from. (In less there's a state not blending 10% ethanol)
Tech Contributor
Joined: Dec 2003
Posts: 19,384
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From: Horncastle Lincolnshire, England
2023 C5 of the Year Finalist - Unmodified
Confused.... Oh boy
I think you may be right though
Le Mans Master
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From: "Atlanta" Ga.
Le Mans Master
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From: Kelso Washington
St. Jude Donor '09, '13, '15
"Quality" vs. Octane.....
It's ALL about the octane rating.
As said before, the higher the octane, the greater the resistance to combustion due to compression only. You want the spark to start the power stroke, not the compression alone.
High compression engine needs all the resistance it can get.
Don't skimp on your fuel just to spend it later on repairs....or bus fare.
It's ALL about the octane rating.
As said before, the higher the octane, the greater the resistance to combustion due to compression only. You want the spark to start the power stroke, not the compression alone.
High compression engine needs all the resistance it can get.
Don't skimp on your fuel just to spend it later on repairs....or bus fare.
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St. Jude Donor '12
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Melting Slicks
Joined: Mar 2005
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From: North Port Fl
The way I look at it, if you can't afford a few cents more a gallon to make the car perform the way the factory built it to perform, you can't afford the car. Go buy an economy car, but that's just my opinion. Buy 91 octane or higher.
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