A common failure point on 3800 engines is the lower intake manifold gaskets. These gaskets fail over time creating small vacuum leaks and coolant leaks.  In worst case scenarios coolant leaks into the oil and ruins the engine. Avoid a problem before it happens by replacing your gaskets before they start to leak.

These are revised GM aluminum gaskets that will replace your stock plastic gaskets.  2004+ Grand Prixs already have these gaskets.