The auto parts guys and the sealant manufacturers push the concept that gaskets need sealants. You would think that gasket manufacturers know what they are doing, especially those like Cometic. If you need a sealant, especially silicone, there is a gap that needs to be filled, and that should be addressed by a machinist. Furthermore using silicone on engine parts is falling out of style. Too many engine builders have found damaged engines due to the silicone finding its way into oil passages. Engine builders like for Indy Cars F1 and NASCAR do not use silicone on their engines. Many (like Cosworth, Ferrari, and Rolls Royce) use Hylomar which is a non-drying compound. There, the parts can be removed and replaced without cleaning off the residue. This is a great advantage when rebuilding engines at the track in between rounds.
