For DECADES I have used a tiny bit of Vaseline on the helicoid threads. Also, I use Vaseline on the much finer threads that allow the helioid (usually) to screw into the body of the lens.
The real trick here is to be careful with how much you add. The fine threads need very little; otherwise, focusing in cold weather will be stiff. On the helicoid, itself, also use it sparingly, but use a bit more than on the thin threads. It might also be productive to add a tiny dab into the focus guides, in order to avoid any 'play' as the lens is focused.
And, to those who would counter this choice of lubricant, I say to you this: Why have lenses which I did this to decades ago not suffered at a result? What works, works. - David Lyga