At 100 degrees C, why is Mobil 1 5W30 more viscous than their 10W30?
See https://mobiloil.com/en/motor-oils/mobil-1/mobil-1
Also, which is the more important value to look at: Viscosity at 40 degrees C, or Viscosity at 100 degrees C?
Regular vehicle is a Prius, and it doesn't show engine temp...