Here is my comparison between Mobil1 0W-40 and Valvoline Synpower 5W-40.
Things I wanted to bring to your attention:
1. Iron content: you can see it gradually dropping from 30 ppm all the way down to 5ppm.
2. Flash Point: well above 400F and again, a gradual improvement over time.
3. Lead: Again, massive drop compared to Mobil1
That's the kind of stuff that really made the decision for me to stick with Valvoline. Unfortunately, BMW still has not approved the 5W-40 grade although it does meet and exceed the BMW specs. Its a sad thing, because the 5W-40 comes with TBN of 11 and all other grades are TBN of 7 or 8.
For me, the good news and hopes are that Valvoline Synpower 5W-40 is currently PENDING approval by BMW. This is a fantastic oil and can be found anywhere in the autostores.