1998 Buick Lesabre

Hi I have a 1998 buick lesabre with 72,000 miles, the engine is the 6 cylinder 3.8L series ll. Everything runs great my only concern is what could happen. I have been hearing there are issues with the upper and lower intake manifold, a possible defect causing antifreeze to spill into block. When it comes to engines I am not really educated so I hope that was explained the right way. So can this be prevented? What are the trouble signs to look for? Should I even be concered? Any feed back would be great Thanks :D