[Bill Pritchard]

As others have said here, it's the flare that does the sealing, <span style="font-weight: bold"><span style="text-decoration: underline">NOT</span></span> the threads. If you are depending on the Teflon tape - or whatever - on the threads to do the sealing, you have a problem elsewhere. Using a small amount of lubricant on these threads or the back side of the flare is a good idea. These are <span style="font-weight: bold"><span style="text-decoration: underline">NOT</span></span> pipe threads like are used elsewhere on the car (i.e., threaded coolant fittings)....pipe threads <span style="font-weight: bold"><span style="text-decoration: underline">DO</span></span> depend on the threads for doing the sealing, but brake line and fuel line fittings use a regular machine thread, that is only used to pull the flared fitting portions tight against each other.