Dealer filled with 0w20 at the last service 6 weeks ago.
That is the wrong oil, 5w30 or 0w30 but not 0w20.
Ah yes, the oil spec did change in the late 7.5s, should tell you the correct grade in your handbook, or ive seen mentioned a sticker on the engine or in the engine bay??
508 or 509 spec is 0w/20 though??