Contrary to popular lore, thinner is better when it comes to oil doing its job. It does best at about 250 degrees. The old saying that says something that "can't get out of its own way" applies to thick oil, when it gets in a tight spot it does what they call shear down and leaves bare spots. Thin oil removes heat better and thick oil contributes to heat by being harder to move around. For example YS recommends lower viscosity oils for the fuel injected ones so more oil will flow past the piston to the lower end.

Please don't let this wonder off into automobile or motorcycle land as these kinds of discussions sometimes do.