These days of high gas cost brings up the obvious question: What is the real problem in using lower octance fuels (e.g., regular) in a C5?

 

This subject comes up often and always generates a heated debate. As you just joined the Forum don't take some of the comments to heart.

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 to use 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 the extra 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. And BTW, I pay over $10.00 a gallon for my gas so its a significant decision to spend even more.

 

GM Owners Manual says you can run 87.

Edit: Deegee got to it before me. But yea what he said.

 

My vette is my DD, I use 87 for just city and highway driving. If i plan on doing some spirited driving ill use 92. the 87 hasnt greatly affected my fuel economy if at all. just my .02.

 

ditto deegee, I use mid grade 89 on road trips and if strickly in town (car is weekend driver) I go with premium (91 here). I lose 2 mpg when I tried 87 on road, 89mid or 91+prem on road makes no difference for me. bottom line: performance need prem, 91+, dailey mid is ok.
flame suit on ... please no comments about buying a perf car and use of non prem gas, everyone does not have deep pockets even if they own a vette, Z or any other perf car. times are tough for many.

 

Your savings would be minimal!

 

91 cost 20 cents more then 87. Average fill up equals $3 difference.

If you fill up once a week you're looking at about $150 per year savings by using 87.

If you can not afford the extra $150 per year then sell the Vette and start riding a bicycle.

 

 

Is the forum search button broken again? Darn that thing! Well, it has only been a few days since the last octane thread, I guess we were due for another one.

 

I'm on the edge of my seat waiting for the next BSM poll.

 

If you can afford the Vette, and most of the mods people put on the car, you can afford the Gas.......

Come on boys, Vette people are not Cheap!!

 

A few extra cents per gallon for 91 or 93 octane gas is better than shortening the life of my engine (potentially)

Just imagine if you had to pay $10 a gallon like DeeGee

 

Well here in Southwest Ill. we have 87 reg.,89 mid and 93 prem. Fortunately I have a station about 2 mi. away that sells shell 93 for the same price as others mid grade (usually 15 to 20cents a gallon less than other stations) The really odd part is this station is part of a local quick mart type chain. This one is on the edge of town. Another one of their other stores about 4 mi.further in town sells the same gas at 15/20 cents higher(like all the other stations in town) So for now I'll run premium for the price of mid-grade!!

 

That's a situation to be in

 

I can see I stepped in one here. I learned a lot. Thanks for all the information: the tech data, about forum techniques, and ways to look at the issue. Frankly it was all useful.

 

My Vette only snorts High Test and Meth

 

As said previously i think the computer in the vette knows your being cheap and reacts later on with reduced performance.

With that being said Its best to follow the owners manual 91 octane.

Well how do you do that you might be saying?

As you scratch your head - the evil oil companies must have teamed up with GM as surely GM knows you can only get 87 / 89 / 93 (or 92) in most cases.

Therefore it is logical to assume you will either underperform your LS1 or spend too much buying octane you do not need!!!!!!!!

Solution: I bring a calculator and a pencil to the gas pump.

If you fill up 56% premium 93 then shut down the pump

Then restart it and fillup 44% Regular 87 octane

Whamo!! You have 91 Octane!! and you saved money.

The tricky part is knowing exactly how much you must put in of each

sometimes this will require several pump re-starts.

At the end of the day you will be a pro at pumping 91 gas and saving money too!

Screw the gas company and the people behind you idling for 30minutes... Afterall you are smarter then GM and Oil's big brother plan to make you overindulge!

Pump on brothers and sisters!

 

We just had a Gas War here. Hard to believe we were getting excited by $3.66 per gallon. One station is still low ($3.77) You would not believe the lines of cars. I would guess some of them waited 15-20 minutes.

This thread should be a sticky. Maybe then we won't see a new one tomorrow.

 

High gas prices actually mean premium is a better deal, since the price difference between the grades has hardly changed! Most stations around here still charge about .20 more for premium.

If you drive your Corvette 15,000 miles for year and you average 20 mpg, then you will consume 750 gallons in one year.

As someone pointed out, the cost is about $12.50 a month more for or $150 a year.

Switching to 87 octane will save 5% on gas at today's price. As prices increase that savings becomes less and less. It just isn't much!

If you want to make a real change, then simply find a friend to carpool with you. You will save 50% on commuting costs!

 

Why don't someone just write one as a "Sticky".