Mercedes Benz repair: oil in air filter, mercedes 300d, oil separator

Question
I get a little oil in my air filter, air filter compartment, and it seems to come through a hose that comes off the top of the engine and into the top of the air filter.  
I have heard air is important for diesels and I would like mine to run well.  

Is this a problem or is it normal?
Also, what does that hose on thop of the air filter do?  It comes into a little cylinder shaped container and then has oil drainage underneath (?)


My car is an 85 Mercedes 300D and I have been running biodiesel (B100) for the past 2 years.
matt

Answer
Hello Matt
B100 :COOL:, Please come join us on:
http://www.mercedesshop.com/shopforum/forumdisplay.php?f=15

There are many alternative fuel people there.   

The hose is CCV = Crank Case Vent.
The cylinder is Oil separator, which connects to a drain tube under the filter housing, (the tube needs a new O ring every few years).