My choice of synthetic motor oil: whatever is on-sale and/or w/ a rebate-promotion!
Which means: Mobil 1, Quaker State Ultimate Durability, Pennzoil Platinum, G-Oil, etc. I don't run extremely high HP applications, so a quality synthetic lube is a-ok for me provided it's changed regularly & paired w/ a premium oil-filter along w/ periodic air-filter servicing.
Does anyone know what Mercedes Service Dept uses for their synthetic oil?
In Europe, the factory fill for the AMG & Brabus models was
Aral! It was a surprise to me, but then I researched further to learn that it was an exceptional high-weight synthetic motor oil.