Loc Tite also makes a teflon type tape, stuff works good, it's kind of sticky so it's easier to wrap. It also makes a teflon type string.
Some tips with teflon tape, from a guy that does both plumbing and hydrolic. there are different kinds of threads, cone and straight. Getting teflon to seal on straight threads is tuff and it will never really tighten well. What happens is you tighten till you run out of threads and then the non threaded part stretches the female part (and really doesn't help with the seal). Or in plain langauge tighteng a cone type fitting actually tightens something. Tightening a straight cut fitting doesn't.
There is some stuff called Leak Lock (or maybe it's Leak Loc), that works well. Sets up just about as hard as you can get and still possibly remove it sometime (good to over 400 PSI probably 600).
Teflon tape, I wind it so it makes it's own cone (same with any wrap/string/hemp/whatever), one layer for the first wrap, then two, then three. You wrap it with more overlap with every turn (technique). If the teflon tape is too wide, split it down the middle. Like one old timer told me, the first wrap really doesn't seal anything, the last wrap does.
Good old fashioned Permatex works as good as anything else. Two grades hardening and non hardening (the non hardening is hard). *Hemp*, a slight wrap with hemp, then a finger full of prematex and just snug it and let it set up. Hemp is good stuff (just try to avoid any/much, inside the system, as best you can), hemp swells when most anything liguid comes in contact with it, the fibers help strengthen the bond and when you go to remove it, it tears and helps with removal.
Stretched threads and moderate pressure (under 200 PSI). Coat the threads of the male side with a little car wax (a very light coat), use a two part epoxy (metal mender). It will seal up good and can be removed. Just have to make sure it's clean, clean, clean.
When using a wrap on hydrolic fittings, I try to keep as much of the wrap away from the inside end as possible, but you need some to get it started. Just try to minimize it. I've been doing it for thirty years and haven't had any trouble yet. But the possiblity exists, that a little piece of teflon (or hemp or whatever) will get caught in a valve someplace.
When I put a tranny temp. sensor into the pan, I got a couple of large brass nuts (the thin type), drilled and tapped them for the sensors thread and made jam nuts. A couple of turns of teflon, actually stacked a little so when the jam nuts were compressed the teflon flattened and made a seal. Just snug them. I ended up silver soldering one jam nut on the inside of the pan (just being anal) not really necessary.
I also keep a roll of graphit thread (and string and rope), Stuff works as good as any high tech stuff, just like hemp does. Graphit string and rope is handy to have in the tool box, you can wrap it around a shaft, use it in place of teflon tape and make a temporary seal (even hammer it in there bit). Sometimes low tech. works just fine.
