Oh please. You've got to be kidding. Look, go prove it to yourselves, and screw the "facts". Stick a quart of Mobil-1 15W-50 in your freezer along with a quart of whatever else you're considering, like the 0W-40 or 5W-40. And of course at least one dino oil like Rotella 15W-40. Better yet, if it's well below zero F where you live, just stick them outside overnight (most freezers don't get much below zero F). Try pouring each of them when they're fully cold-soaked down below zero F. Then tell me how 15W-xx dino oil is almost the same as 15W-xx synthetic and that engine pumping is a big factor.
Based on the provided CCS data, Rotella Syn "outperforms" Delvac-1. And it's fairly common knowledge that D-1 is not even in the same class as the cheap-o Group III Rotella "synthetic". This hoepfully should point out that there are numerous factors to selecting an oil and you shouldn't make a decision based on one specification alone.
On a side note, this being a MERCEDES forum, Mercedes-Benz could care less what the API ratings are for oils. They have their own approved lube sheets and only allow API specs as a deciding factor probably for legal reasons, and that the Euro specs aren't used over here in the 'States. Saying M-1 is not as good as others only based on their "inferior" API rating is, IMO, inflammatory. Amsoil has no API ratings at all, so that must be real junk, huh?
(flame suit ON)