I dont use teflon type tape (plumbers tape) on electrical single pole senders as there is a chance of not getting an earth through the tape.
Loctie make a great teflon based goo that I have never had an issue with, it seals VERY VERY well, even when not super tight, has a very mild thread locking, but removes with hand tools. It is white but cleans up very easy and paint etc should not be affected.
Loctite 567 paste, a single tube should last the average car guy lifetime.
https://www.henkel-adhesives.com/sk/...ctite_567.html
I have been a plant mechanic (heavy desiel fitter) for over 30 years, rebuilt hundreds of engines, transmissions, final drive and alike, this product, is the go to for sealing up rebuilt components that you dont want a warranty claim on.