al wrote:

A bloke I know swears by putting PTFE around the olives before
tightening the compression fitting. Seems to work. A bit of normal
threadlock on the threads - as much to stop it seizing/binding as to
stop water. The olive seal is what counts for stopping water, not
the thread.

Gease/oil on the threads might stop them binding (it works fine on car wheel
nuts) but threadlock can only lead to trouble.