-2006 Pontiac Grand Prix GT, automatic, 106,000 miles-
I am 19 and going to college this fall. I bought my first car yesterday, an '06 Grand Prix GT, great condition. The dealer revealed to me partway through the transaction that the engine was supercharged which confused me, since in all of my hours of research I had seen the GTP to be the trim with the supercharged engine. The engine certainly is supercharged, anyone know what that could be?
He also recommended I use premium fuel. I have a good job but I'm about to be a full time student and premium fuel would hurt my pockets a lot more. How necessary is it for my car to receive premium?
Find the owner’s manual. If the premium is not required, you can use gas with 87 octane.
If it is a GT and not a GTP, someone added the supercharger to the vehicle.
In that case, they likely tuned the car to run Premium only. With aftermarket forced induction, Premium fuel is an absolute MUST. If it is tuned for Premium and you run Regular, you will damage the engine.
I agree with Yaser to check the owners manual. But don’t be surprised if it specifies at least 91 octane. The point of forced induction (turbos and superchargers) is to increase the intake pressure within the cylinder. Then, with the compression stroke of the piston, you can generate even higher pressures at the time the spark plug fires. However, when you raise the pressure in a gas, you also raise the temperature. If the temperature rises high enough, you can ignite the fuel. (This is how Diesel engines run without spark plugs.)
unfortunately, if the fuel ignites before the piston reaches the top of the compression stroke (preignition) you will have the rod and piston driven up by the crankshaft and down by the fuel combustion- at the same time. This is bad and can damage the engine. High octane fuel ignites at a higher temperature, and therefore prevents preignition.
Modern engines can detect this and adjust the amount of fuel and air that go into the cylinder (reducing power and fuel economy), so that low octane fuel doesn’t damage the engine. But it isn’t optimal. And with that particular car, I would be very careful and follow the manufacturers instruction.
Good luck,
In 04 the gt is now the supercharged model and the gtp is a 5.3 l v-8. The gt model is programmed from the factory to run on 87 octane fuel.
