I remember hearing this story, shortly after Fiat took over Chrysler they made the move from Mobil to Shell, as Shell was already receiving the endorsement form Fiat. It pertained to 0w-40, I have a friend who at the time owned a Dodge that specced 0w-40 (maybe a SRT Challenger) and Mobil no longer met the updated spec released after the takeover, and no dealers had yet received any of the approved Shell. He lives in Ontario and maybe the supply chain doesn't move as fast as here in the states, but I instilled in him the Mobil he had used previously was fine. At the time his car was still under warranty and was reluctant to deviate from what the Chrysler dealer had told him.
He has since sold the car and I think at the time he had to wait forever before an oil change.