Roadtrip makes an excellent point about cleaning the studs and then applying anti-seize before reassembly. Makes life much easier if/when you need to remove the head. To also minimize corrosion, change the antifreeze at least every two years. I do it every year, which is probably overkill, but antifreeze is cheap. Modern antifreeze contains an additive that keeps it from being an electrolytic solution, but that additive has a finite lifetime, and eventually the dissimilar metal problem will raise its head. There was, locally, a GTV that had been parked in a garage for ten years with old antifreeze in the cooling system. Much of the cylinder head had been chewed away, and the spark plugs had actually fallen into the cylinders.