After I put this plug in, I tried to pull it back out some to clean the edges one last time with acetone. I couldn't budge it. It won't be moving even without the JB Weld. With the JB Weld added, it's permanent. I also don't trust the head gasket on this thing, either. It's going to get a bunch of miles close to home before it goes any distance. If this plug were to move, it's only a few minutes to pull the radiator out and cross pin it. As far as threading it for a plug... the walls of this tubular piece are only .100" thick. A pipe tap is tapered and that means a plug is putting outward pressure on the hole it's screwed in to. I've already replaced the expansion tank from cracking and I think it would be inviting the same problem with the raiator several years down the road.