Loctite® PST® 565™ thread sealant is recommended for sealing all types of metal fittings with tapered threads, from NPT plumbing adapters to the transaxle fill plug on the Hewland Mk 9 gearbox.
The unique formula acts as a low-strength threadlocker to resist loosening from vibration, but it also acts as an anti-seize compound, allowing for easy disassembly without galling. Much easier to use than sealing tape, and you don't need to worry about bits of it breaking loose and clogging filters. Resists heat up to 300°F. 50 ml tube.