one of the main ideas behind it is it creates a film on parts and provides a dry lubricant if oil were to stop flowing. i had an oil line blow off and drove a while before i noticed smoke smell(was at night), i'm convinced this is what saved my motor since it had 3 quarts out of 11. i tore the engine down(due to piston top chipping of due to lean condition) and all bearing surfaces, crank journals, cams all looked like they had 10,000 miles not 77,000 miles.
i have also seen pictures on here showing how it coated the cam lobes on and engine i can't remember. i'll try to dig it up.
I've posted some pics before, that's an old diesel. Right is 30 miles after adding MoS², left shows how it sticks in 190 miles. Engine runs nicely, but I was hoping to get significant mpg benefit and now it's hard to measure. Maybe this engine was too good to start with, hot idle oil pressure was slightly below 2 bar before MoS² and it's still the same.