To my mind, the 2 top products are Caswell Plating
and Bill Hirsch
. The Caswell leaves an epoxy coating that can seal pin holes and other irregularities. It is also very
useful in restoring Norton and BSA fiberglass tanks. The Bill Hirsch product is a coating that stops the rust and protects the metal, but will not seal leaks. So it depends on your tank's exact needs.
After discovering Caswell
epoxy coating about 10 years ago our shop has used nothing else. The Caswell web page answers your question and says to use the "shake, rattle, roll" method with sheet rock screws
. The Caswell epoxy method is one of the few that tell you NOT to remove every scrap of rust simply becasue the rough surface helps it adhere.
We are now getting in bikes that used Kreem about 10 years ago. The stuff is awful. It comes off in big sheets (looks like latex paint) and clogs your entire fuel system. Then you have to stop and remove the rust AND the Kreem. I can only say if you use Kreem that you will be exceedingly sorry
down the road.