Hi Sixto,
First, I tried emailing a response to your private question, but your email account had "exceeded quota" and the messages bounced. I'll try to re-send the info tonight.
Second, about the oil leak. No, I don't really have any new info. I have thunk about it though. :p I'm 99.99% sure the head itself is fine, and the gasket is OK too. I'm almost positive that the problem is the valve seals or guides. The intake & exhaust valve stems are about 1mm different, with different seals. I plan to pull the cam and see if they are backwards or not (they are color coded). If they are OK, the only other thing could be the guides. However, aren't the seals supposed to keep oil out of the guides in the first place? Hmmmm. I'm hoping it's just the seals! If it's the guides, as psfred mentioned, I'm gonna have to get medieval on the machine shop that screwed them up (and they do a LOT of Mercedes heads, including diesel heads!).
I put nearly 4000 miles on the car in the last month and the symptoms have not changed. Car runs great, oil leaks from the exhaust manifold. Now it looks like I might have a slight seepage from other exhaust ports too, not as bad as #6. Which again points to valve guides/seals. The #6 port could be worse because the exhaust gas must flow from front to rear, the the entry to the turbo is via the #6 port, so oil could blow back and collect there from the other ports.
I may not be able to do much with the car over the next 2 months. I may be moving out of state VERY soon and yanking camshafts for fun is not in my schedule! After I settle down again, post-move, I'll be able to do more investigating. And maybe replace the head on my other 1987 300D! Yippee...
Best regards,