Lubricate both O-rings and threads.
from: http://www.anchorrubber.com/specialty/parker_o-lube.pdf
And some "light" reading here about thread lubricants:
https://books.google.com/books?id=N...AQgeMAE#v=onepage&q=lubricants thread&f=false
from: http://www.anchorrubber.com/specialty/parker_o-lube.pdf
3.1.5 Lubrication
Lubrication of O-ring seals is extremely important for installation and operation of dynamic seals as well as proper seating of static seals. The general rule for use of lubrication is: The greatest benefit in using a lubricant is obtained during the initial installation of the O-ring
And some "light" reading here about thread lubricants:
https://books.google.com/books?id=N...AQgeMAE#v=onepage&q=lubricants thread&f=false