E320 Leaking Oil
There is a lot of useful info here about oil leaks out of the M104 engine which is what you have. Try some searches such as "M104 and oil and leak" or "E320 and oil and leak"
If the leak is up front, it is probably from the timing chain cover. If its from rear, its probably the head gasket.
Remember that the fan can blow oil around so cleaning everything good then driving a day or two and then looking things over may lead you to the problem.
I'm very symphathetic as I just put my '97 E320 in the dealer shop for the fourth time regarding these leaks.