Just swapped a new battery in for my late father-in-laws 2005 Grand Prix GT with about 150k miles. It started right up no problems and electricals look great. However, after about 2 mins of running grey/black smoke is coming off the engine basically right at the top of the exhaust manifold front side of motor/below the heads. Also, white smoke out of exhaust tips.
I know nothing about these motors does anyone have any idea what that means? I have a check engine light but no way of checking what is causing via OBD
