Hi,
When these cars were new AMG recommended Mobil One, for that reason that is all I ever used in mine.
Bought from Euro Car Parts, with one of their discount codes.
Nothing wrong with Mobil 1 but you don't have to use it. It was just the best deal on the table at the time...
If you're going to believe the hype then surely you'd want to use whatever their latest recommendation is as research and thinking updates. For example, M156 was 0W40 and is now 5W40.