Is Formula Shell pretty much identical to PYB?
No, its a lot closer to QSGB IMO but still not identical from what I've been able to tell from UOA/VOA's.
2004 Jeep GC WJ 4.0 @ 123k Pennzoil YB 5w30 - MoS2
Napa Silver 31516
KIA Sedona 41k, Chevy Lumina 174k, Chrysler Sebring 172k, Chrysler Concorde 97k