I was just reading this guy's oil blog. It's pretty interesting. He ranks AMSOIL SS 0w30 at #12, Mobil1 5W30 at #10. This is all based on film strength. 5W30 AC Delco is way down at #90 (this is the free stuff that GM puts in my Cruze). I will be upgrading to Mobil1 5W-30 for my next oil change, and now we know why so many manufacturers recommend and test most heavily with Mobil1.
https://540ratblog.wordpress.com/201...-test-ranking/
It was interesting to see some conventional oils place so highly. The other oil that I was considering, Castrol Magnatec, didn't do so hot (#100). Granted, this test doesn't really capture its claim to fame, but I still probably won't use it. Royal Purple generally did poorly.