I was asking a friend of mine about materials that would hold up well in the role of coolant o-rings, and he mentioned Oatey Plumber's High-temp Grease. I've never heard of this sort of thing being used in an engine before, and I was wondering what you folks thought?

Also, I've heard of people using silicone and teflon seals... I want this motor to last, so what's the best choice here for a streetported motor?