Always PTFE tape. Seal it with a loctite can make removal difficult and too much force shoud be avoided because of the thin metal of the tank.
Never used ptfe, but it obviously works well. If using loctite, right type and right amount.
About the 243, it's a soft one, needs just a small drop or two on parts of threads to secure and stop leak, & will unscrew without any real force.
Got 3 bottles of Loctite for different use, green (hard), red (medium), blue (soft).