I'm a little different. I don't see anything wrong with using silicone, if it's used correctly. As moper pointed out, it's a good idea to use it around coolant passages. But I usually don't use any on water pump gaskets. I like to use it around water ports in heads. I know...it's a slant. I don't like cork, though and that's one place I use silicone. To replace cork. I wouldn't use it on the valve cover, because you have to remove that for valve adjustments and I think there's a nice rubber one available. But the oil pan, I would chunk the cork in a new york minute and lay a nice neat bead of silicone in its place. I will also use it on bolts to keep them sealed if they go into a water jacket or into the crankcase or to keep them from seizing up as in exhaust bolts or studs. remember to use high temp red on exhaust fasteners. Lastly, if you run computer controlled fuel injection, make sure your sealer is sensor safe.