Originally Posted by xluben
These are good pictures and a very common problem. Even at stock boost this can occur, but any increase in boost makes it much more likely. A bit of oil in these components is normal. I wouldn't worry about it, but maybe check it once in a while because that does look like a somewhat decent amount.
EVERY 08+ WRX should remove those rubber end caps from BOTH ends of the throttle body hose. You should also add a zip to to the vacuum line that goes from the top of the BPV to the back of the intake manifold. The nipple on the intake manifold does not have a barb and can easily slide off.
What exactly is the oil from? I've read that it's blow by and it's a result from the ringlands seals not being perfect and oil slipping past them. Shouldn't it be no oil at all? I need to find a good read on this