Best way to seal outboard header studs?

[superdart]

My left front header "stud" was never there, and I was using a bolt instead. Since I have it out, I am installing a proper stud in the head. What should I use to seal it up so that it doesn't leak coolant?

Teflon tape?
Ultra Black, Gray, or Copper RTV?

Non of the above?

 

[daredevil]

I use a teflon based pipe dope for plumbing connections available at your home depot or lowes