hose between air filter and engine

I have a 89 grand am (2.5) and between my air filter and and my main engine( dont know what to call it, where pistons at) there is a short hose. Oil is traveling up this hose to the air filter and of course making it dirty, quick. And there is a mini filter like piece to prevent the oil from going to into air filter. I seem to be having a lot of oil going into my air filter. Is this supposed to happen, is this some kind of oxygen sensor?
PLease explain

.... Im pretty sure this is supposed to be a vacuum hose, not an oil drainage...

I'm having the same problem, did you find any answers?

I believe it's just a vent tube that vents your crankcase when your PCV valve isn't quite doing the job. You may want to check/replace your PCV valve. It's generally an inexpensive part that can be picked up at any auto parts store. I have even seen them at Walmart for some cars. Very, very easy to replace. Generally no tools at all. The pcv valve can be found on the top of the valve cover on most cars. May not be that far from the vent tube that you are talking about. Looks like a little plastic elbow. When you take out the pcv valve it should rattle if you shake it. If it doesn't it's definitely plugged.

This happened to me as well, the amount of oil was considerable. I have the V6 and the intake manifold gasket was blown. No overheat of engine, just a loss of some coolant I couldn't explain and that oil in the hose you're talking about. Check for water in your oil. Hope it's just the pcv valve but I doubt it