WOW !! What a great forum. I recently got a 1998 Pontiac Grand Prix GTP with a 115,000 miles. It was orginally in Fl so I am a little worried about winter here in the Windy City. Here are my questions.


1.) What would you recommend using instead of the Dexcool . I have been reading your posts and seem it's a good idea to flush it out.

2.) What is a good brand for the super charger oil change.

3.) Just in the last 2 days I have notice when I am at a complete stop and the car is in drive there is a strange rattling coming from my engine, but once I press the gas or put it in park it's goes away. It does not make the noise when driving or when pressing the gas in park.


Any help would greatly be appreciated.

Welcome to AF.

For the supercharger use GM SC oil part number 12345982.

Remove the SC drive belt and see if the rattling sound goes away. If it does then you probably have a bad coupler. If noise is still present then it could be a belt driven component or accessory or tensioner/idler pulley associated with the main drive or supercharger drive systems.

On the coolant. You can use coolants like Prestone Extended Life 5/150 but be sure all the old Dex-cool gets flushed out. If you are having no issues like any visible signs of sludge in the cooling system then you could stay with the Dex-cool. In any event the Dex-cool is only good for 5 years or 150K miles, whichever comes first but the same is now applicable to the aftermarket coolants.