Have been digging around and it seems that the fuel to go with is 91 octane but have read plenty of articles and or posts of people using the lowest grade 87 octane.
What do you guys use and is there any risk using 87 octane?

 

The owner's manual should have a page that talks about fuel, and that is the correct information, so that is the first place to look; and the only place you really need to look.

If it is like the other 2010 GT's, it has "adaptive spark timing" which allows it to run fuel with octane between 87-93. The system automatically advances or retards the spark timing to take advantage of the octane that is in the tank. The higher the octane, the more advance it will run and the better the performance.

For a GT500, even though it probably isn't actually required, I would run the highest octane fuel I had readily available; which is probably 93 in your area. If you have the budget to buy a GT500, I would assume that a few more dollars for gas is not a big problem. This will give you the maximum performance from the supercharged engine, and avoid any potential problems with the system not working right with lower octane fuel.

 

yes thats what i have been doing, 93 since its the best available here. Just thought Id check as alot of articles bash premium Gas as a waste of money.

 

Which grade does your owners manual recommend? You would think it would recommend "Premium Unleaded Fuel Only" being that you have a GT500 with factory supercharger. At any rate, I wouldn't run anything less than 91 octane fuel.

 

IIRC race fuel still contains lead and can be purchased at certain locations. However, your vehicle also requires an aftermarket tune in order to use it.

 

It depends on whether your car is designed to take advantage of the higher octane; I believe yours is. (the Owner's Manual will tell for sure)

But yeah, there is a lot of confusion out there on this. Some people think higher octane has "more power" but it does not. Octane is only a measure of resistance to detonation; higher octane allows you to run more spark advance, but if the car does not do that, then it is a waste. Also some premium fuels claim to have a better detergent package than the lower grade fuels; but that is only for reducing engine deposits, has nothing to do with power.

There are two ways your car can take advantage of higher octane:
1) the computer is designed to do it from the factory, like yours (I'm pretty sure -- see Owner's Manual to be sure)
2) you install a custom "tune" that has more spark advance, designed for a specific octane rating