Exactly, precisely and that makes me wonder why someone would choose 5W-20 over 0W-20? Perhaps in the very very hot temperatures but not in the initial start up of the engine, as I would still choose 0W-20.

Btw, I called Mobil 1 tech support today and verified that the best grade to use is 0W-20 for a vehicle that can take 0W-20 or 5W-20. In the end you are ok with either one grade and it comes down to personal preference.