Why? Is this engine not a diesel? It burns it up like fuel, not like it's a gasser and that is an undesirable introduction of oil into the cylinders. Think of it as solving a couple of problems. First it slowly reduces the amount of oil you need to drain, Second it extends your diesel for more MPG and third it can reduce a group of shady characters on the street corner in a few short or long revs of the engine.
I tried to catch the oil in my car to reduce the smoking and it was more pain than gain. Now I just roll with the blue smoke on hard accels.
Hmmm i can see your logic... looking at it from my checkbooks point of view the money spent on a crankvent would buy a lot of blown by oil decisions decisions
ORCoaster has some valid points- it's not the end of the world until it runs away. If you can find one, Mercedes put a kickass oil separator on the 82 and 83 240Ds. I run one on my Pickup and it helps a lot.