If it happened shortly after a service it's probably been over-filled when the oil was changed. Draining a small amount of oil out of the engine should fix it. If that's not the cause it could be a ...

I've driven both and much prefer the Sprinter. The "manumatic" in the Fiat is not good and I prefer the way the Benz sits on the road, how it performs over bumps and its resistance to crosswinds.