There's a MAJOR difference between oil lubrication and shear capacity. Engines fail when the oil is insufficient to provide a fluid bearing between the crank.

Motor oil is one of the most important fluids in your vehicle. The purpose of motor oil is to reduce friction and keep a vehicle's engine clean and corrosion-free
I disagree to a certain extent. Those are only two of oils functions. The most important is to provide a fluid bearing.

  1. Provide a hydraulic wedge for the fluid bearings
  2. Lubrication
  3. Cooling
  4. Cleaning

This is the first thing we learned in auto shop.