Mandatory vs. recommended fuel


#1

I just purchased a 2006 corvette eith LS2 engine, 6 speed auto and 9,050 miles. The owners manual “recommends” premium 91 octane but allows regular 87 octane as long as spark knock is not encountered. There will be a slight decrease in performance. Please offer your comments and advice. Thanks in advance for your time.


#2

If you use 87 you will get reduced performance and lower gas mileage.

I can’t imagine why anyone would buy a Corvette and not put 91 octane gas in it.


#3

If you use 87 octane, you will probably have to drive it with a light foot to stay away from detonation (ping). You probably paid a pretty penny to get this sports car so why economize on the “go juice”. Yes you will pay +$0.20 more per gallon but when you want to romp on it you can without concern.

Bye the bye, when you are loafing along the freeway in 6th gear what RPM does the tach read? What is the final drive ratio? What tires are you running front and rear?

Just curious.


#4

Thanks for your reply - kinda what I thought. I haven’t picked up the car yet so I can’t reply on the rpm question. The final drive ratio is 1.95 and the tires are 245/40 18" and 285/35 19" Gododyear Eagle F1 Supercar run flats (Z51 PKG).


#5

You got it right, but you need to add that in addition to the small loss in power (You did buy the car with power in mind, I would guess, so why are you so willing to give up some power) you will also have a slight reduction in mileage, which could wipe out any savings on the price of the fuel, although it likely will likely not be that much of a loss.


#6

I’m with McP on this one…why would you even ask? You’re buying a sooper-dooper supercar, you obviously want the best out of it. You get that with premium.

Besides, if you post back here in the future saying “I burned a hole in my piston” we’ll scold you pretty badly. Nobody wants that.

Enjoy your new ride.


#7

The car is so overpowered if you use the excess HP encountered with premium fuel more than 2% of your driving time you will either lose your license or be in an accident on regular roads.

Use the regular and listen for knock.


#8

How many people even KNOW what spark knock sounds like; especially, with the other noises and the sound system cranked up? 91,or 92, or 93 it should be.


#9

Yes you will pay +$0.20 more per gallon but when you want to romp on it you can without concern.

Where do you live that it’s only $.20 more. It’s at least $.40 and some places as much as $50/gal difference. But I do agree…Why buy a $50k car and NOT use the recommended fuel.


#10

Can you clarify that final drive number? The diff can’t be a 1.95 (not enough gear advantage I would think something like 3.23 to 3.55 for the diff and the ratio for 6th gear will be less than 1.00


#11

With a fine piece of machinery like this, don’t be cheap about what you feed it.