LazyDog, I would prefer an oil that has mulitple certifications (VW, Porsche, Audi, Mercedes, SN, GM, maybe BMW too). Also, consider using a Mercedes 229.51 or 229.52 oil instead for lower SAPS these days since sulfur in U.S. gasoline is disappearing.
Also, Ravenol tends to use the best base oils (PAO, esters with very little GroupIII/III+) for a clue it might be better. Anti-oxidants in other brands could be better & trump base oil selection, so go by the biggest pile of specs you can find and you can't go wrong. Example: Mobil 1 ESP 5w30 has one of the biggest set of performance specs from so many perfromance tests it passes, we can call it proven. Similarly, Ravenol VMP 5w30, both oils with HTHS about 3.5, perfect for a c-class, meets many performance specs.
... blauparts.com for the Ravenol, amazon.com for the Mobil1 ESP and some flavors of Ravenol, also some autoparts stores.
I can't find a technical data sheet for the Mercedes house brand oil, and their safety data sheet is totally absent of any legal information. You can tell a little about an oil looking at it's NOACK and pour point, although, as said above, there is no replacement for a huge pile of qualification specs !