If you read the reply properly avaarse you will read that i said the thread that screws into the TAP, NOT the compression fitting.
Well that is even worse in my book, using PTFE on a tap connector. Have you ever heard of a washer? I am not being clever, I am just trying to tell people the correct way to do something.
If you use PTFE on the thread of anything other than rad tails/steel fittings and the like - which the manufacturers instruct you too, you are creating a leak waiting to happen . . . .