Oil does thins out when it hot. Some manufactures run oil temp hotter than coolant by 30 degs. Why because it pumps easier less power lost. Oil film yes crank still doesn't exactly ride on cushion of oil. Everytime cyl fires that oil is pushed out of the bearing. If you crank oil pressure really high it will also wash bearings out make them flake and come apart. Oil is coolant for bearing taking heat away so bearings won't seize. Like I said before how does engine that's never shut off wear out? According to some everything rides on wedge of oil so in theory it should never wear out
Well you mentioned it heat! It is a wear factor. For engines under normal use, shutdown and startups, its the most detrimental part of any engine. If you see it as oil to help sliding of the crankshaft contact to the bearing surface, I see it as the same a film of oil of which the crank rides in. As someone stated if you put oil on the floor you will slide wright off. That's the film of oil whether is whisking to slide or film. I see it as the same. If it wasn't a film then the oil on the floor serene wouldn't be as so!!