Not a machinist by any means, but for those wondering about putting sealer on a machined surface, I can tell you that from my shipbuilding career, I know that Naval steam turbines are metal to metal surfaces on the casings. There is no sealant used. "Scrapers" (a dying art) spend many hours mating the casing surfaces on board the ship, but no sealants are used. Just my 2 cents.
