[scottj]

Clear silicone, except for the valve covers where I use the blue, molded rubber, FelPro gaskets.

I run vacuum in the crankcase, commonly refered to as a "sealed engine", so it as to be air-tight.

The silicone is used on both sides of the intake, oilpan, timing cover, and distributor gaskets. It's also used on the waterpump gaskets and on the head gaskets around the studs and coolant passages. Also under all the head washers. It's used again in place of header gaskets and as a thread-lock on the header bolts.

The silicone works so well on sealed engines that the same procedure is used on my vented engine. There really is no excuse for any fluid leaks using modern assembly technique.
Scott