RTV, Permatex, Aviation Form-A-Gasket, The right stuff etc....

I used Permatex Ultra Grey to seal up SBM exhaust manifold studs, it worked where nothing else would. It is now my go to sealer for everything that needs a sealer. Must gaskets dont need sealer if installed correctly.

Yes sir. ...and no matter what, you cannot explain to people how well it works as a thread sealer who've never used it as such. And it does more than seal in the application you describe. It also acts as an anti seize agent, as it does not allow the fastener to rust or otherwise seize in place. It just flat out works.