The car has synthetic in it from the factory.
What is recommended, and what I believe is probably in the car now, is Mobil1 0W-40.
The car's regularly scheduled maintanance is free during the warranty period. If you want to use "your" oil, the "you" are going to buy it and bring it in. That's kind of a waste of money, since MB is more than happy to pay for the recommended Mobil1 oil, why buy your own?
Although MB may indicate that 1000 miles is "the break-in period" as far as watching your driving habits, there is no regular scheduled maintenance at any interval other than when called for via the FSS display.