Loctite, makes a hydraulic fitting sealant that works really well for this application.....but teflon tape should work well also ????Jim

Loctite makes a product called "PST" which is a liquid teflon sealant. It is good from -65F to +400F and cures in 24 hours fully. A large OEM industrial compressor manufacturer uses this on all their compressors.
Most hydraulic and pneumatic supply houses sell it.

WE use Rector Seal (pipe dope) on all threaded pipe installs. We seldom use threaded pipe for installations. Copper water pipe is the best we have found. It is cost effective both in labor and materials. It also does not deteriorate on the inside like steel piping.

Thank you all for the quick responses.
From Napa, today, I bought some Permatex Thread Sealant with teflon. I was thinking of Loctite 545.
Again, thanks