I've heard a few opinions on this, but I would like to hear a discussion and see what people think. The mail threads should not require any sort of sealant, correct? What about O-rings? What sort of torque?

 

What, no one knows the answer to this question?

 

I was told by Stan, the fitting God that AN threads do not require teflon or silicon. And you should tighten them until it stops turning. It will tighten until it hits the other fitting, dont He-man tighten it tho but it make it snug.

 

This is my field all the way. I'm a hyraulic mech on airplanes. Ok if going from a union to b-nut nothing is req. If coming out of a block per say, you need a o-ring and backup ring inside a jamnut. AN fittings have max torque.
Do not over tighten
MS fittings on the overhand have a much higher torque and can withstand vibration better. I prefer MS.