Funny you should mention that.
I have a pound of M1 synthetic here from when I started playing with Garand rifles a few years ago. Most sources indicated this was the lube of choice.
I'm not impressed. My Coastal simply works better. Mind you I'm not preparing for the battle of Chosin. It's warm out or I don't go rifle shooting.
I've tried that Outers stuff too. Pretty much useless.
Gunslick just turns everything it touches black.
Lubriplate plates everything except where you actually want it.
This is all subjective of course. It's always my favorite stuff that gets discontinued.
They even screwed up Elijah Craig.