Have a look here folks.
http://www.whnet.com/4x4/oil.html
The M-B specified oil is Mobil 1
ESP 5 W - 40.
Not to be confused with
any other 5 w - 40.
This oil, according to the chart, is specified for 2007 + models.
Oddly enough, when I inqired at my local M-B dealer's parts counter, I was told they use it only on BlueTec Diesels, and anything else still gets filled with 0 W - 40.