Kevin Cameron writes for Cycle World, and he has an amazing understanding of engineering and what makes engines work.  I have thoroughly enjoyed his articles that describe how fasteners work, the different vibration and bending problems with singles/parallel twins/V twins/boxer twins and other engine layouts....and numerous other design issues that I knew nothing about.

This article goes into a lot of depth about how oil does what it does, and how each engine is designed to use the engine oil effectively.  It also explains why you should not run an engine oil that is thicker than the engine was designed to use.   If you read carefully you will learn that no oil becomes "thicker" as it get warm......it only "thins" less and has the properties of a thicker oil at elevated temperatures.

I was also surprised to learn that the oil pump does not keep the parts separated by the oil pressure - but instead it is the oil viscosity and shear friction keep the oil in the bearing.  The diagram that shows the oil wedge in the plain bearing, and the description about how the oil hole is located to keep the thickest wedge of oil at the location of the highest implied loads was a revolution to me.

https://www.cycleworld.com/story/bikes/the-amazing-modern-oil-cocktail/