You want to use either Teflon paste (preferred by most plumbers) or Teflon tape, but the type specifically made for gas.  I believe it's yellow as opposed to the normal white color.  If you go to the home improvement center, and look around the gas range hook up pipes, you will see a type made for gas. Terry K , who advertises on Samba , sells new fill valve that replace the antiquated auto stop valves. I typically hand tighten till snug, and then go about 1 to 1 1/4 more turns.  Over tightening can actually cause problems, so don't overdo it.

Troy

<<Hey guys, has any of you ever unscrewed the filler valve from your tank to r=
eplace the sealing tape?=20
Last night i finally burned out all the propane and need to reseal the threa=
ds there... Just looking for some wisdom>>