Just a quick question--What are the best spark plugs to use in a Grand Prix?
Background: I went into my local auto parts store to get Bosch +4 plugs for my '94 Grand Prix. I have used those plugs in other vehicles and thought that they were supposed to provide more complete burn, better fuel mileage, etc. in any engine. However, the man at the part store told me that putting Bosch in a GM wasn't a good idea and would actually decrease performance. That sounded a little strange to me. Does anyone know if that is correct?
Thanks!