I've heard of it, never tried it. Thought they took it off the market after all the complaints about blocked oil filters and such.
Moly is a solid. In theory, the oil additives have particles of moly that are tiny enough to pass through oil filters. The problem is that, in the real world, filters will stop a small percentage of particles much smaller than they are rated for (kind of like TR3 air filters will get dirty with dust that would easily pass through the coarse wire mesh). In a recirculating system like an oil sump, each pass may only trap 0.01% of the smaller particles, but after a few thousand passes, most of it will be in the filter. Once the filter gets loaded up, the bypass valve opens, and most people don't know the difference. But some people notice things like that, and complained.
This is fairly typical of the stories I've heard. Of course, you can't believe everything you read on the Internet, but I've just never been interested in taking the chance.
https://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=285055