"All their Group II and Group III comes out of Richmond"...uhhh I respectfully can say that is not true. Chevron trades/buys for some group II/II+/III.
Why would SOPUS(Equilon Refining) (Shell Oil Product US -- Formula Shell, Pennzoil, Quaker State, Wolfs Head, etc...brands) send base oil to California from Texas, when Chevron needs it there in Texas and has excess in Cali? Many group II refineries license the technology form Chevron...so the base oil is the same essentially.
As for some concern over formulations, I would let the UOA speak for itself. The only thing a brand has is the "promise" consistency of its performance in use and ongoing quality...I do not think any big company is going to lessen those standards. There is just too much to loose.