almost any of the stuff that is used on gas line fittings... like you can get at the hardware store.... it is thick when it goes on, and in time the carriers will evaporate out a little and it will get even thicker and will set the fitting so it will take a wrench to remove it in a few months.That could work fine, I was locked into thinking the elbow needed tightened down all the way.... What sealing compound should I use on the elbow to secure and seal it half a turn before tight?
BTW, I've only gone hand tight so not too much risk of breaking anything...
i would steer away from the liguid teflon as it isnt as thick...