Thank you for your answer and help!

It is funny you should say that, and now when I look at the pattern of the oil (on the pictures before the wash) it makes sense. That beam in front of the transmission has blocked some parts of the transmission (that are oil free) and has some oil on it self.

The funny thing is that when I checked the oil level last time it was 2-3 mm over the max on the dipstick. So I thought that it is strange because I bought the car 2 months ago, and 1 month prior to that it had a service at a mercedes workshop. So there is no way that they would overfill the oil. Then I smelled the oil and I think that I can smell gasoline on the dipstick. Could it be that a injector or something is letting gasoline into the engine and that the engine oil combined with the gasoline makes the level too high and overflow somewhere, hence the leak? Since I discovered the gasoline smell I have only driven it when I absolutely had to because I believe that the oil inside has lost its lubricating function.

Checked the coolant level also and seems to be ok, but it is green to the color. Will change it asap to the mercedes orange you where talking about. Below are a couple of pictures that I took at the same time as those on the transmission, if you want to take a look.

http://public.openmindedprojects.com/c200engine/

If anybody else has a input that could be helpful I would appreciate if you would share it with me. Regardless if it is about the transmission or engine. Could it still be a leak at the transmission or is it pretty certain that it is leaking from the engine? (You guys have obviously seen these kinds of things and have more experience then me)

Kind regards,
Boris