blue loctite works. Teflon tape is acceptable IF you apply it correctly: start wrapping it holding it back from the first two threads so you don't have boogers of tape escaping the threaded hole bottom. You also have to wrap the tape in the correct direction. The wrong way will ball up the tape and unravel it when you screw the thread in. The right way eases it in. If you look at the male thread end-on, it should be wrapped CW.
