I'm replacing the gasket, exhaust flange, nipple, and exhaust riser on my Universal M25. I went with new parts - the riser is the Westerbeke #200266. What thread sealant should I use on the high-temperature threads connecting the flange - nipple - riser? Do I use the same on the raw water connection at the top of the riser, or just use some thing like teflon tape on that raw water connection?