it could be shagged oil seal on the turbo etc. some people fit them to catch heaps of oil in the intake, this isnt a fix its just masking the problem. When you start making lots of power – or the engine is tired and in need of a rebuild for that matter – the plumbing of crankcase gases needs more attention (i.e. if you do fit one and it keeps filling up time to fix the source of the problem. I wouldn’t recommend option #4 as it blocks the PCV entirely. Option #1 is the easiest while option #3 is the most complicated but will vent slightly better. In the instruction document you sent us, the first three options will work okay for your application and it’s just a matter of which plumbing configuration you want to use in terms of connecting the cam cover outlets to the catch-can. This way everything is still sealed to keep the authorities happy, the PCV setup still works as intended and the catch-can can be put to use to remove excessive oil from the blow-by gases and minimise oily fumes being ingested by the engine from the PCV/intake system. Therefore, when fitting an oil/air separator (commonly referred to as a catch-can) you’ll have to plumb the can in between the ports on the cam covers and the factory PCV valve, to act as a cleansing device of sorts if you will. Check out the above illustration of how the average turbocharged. This is bad because if nothing is done, this excess gunk will build up in the intake manifold, coat the intake valves, coldside of the turbo, intercooler, and intercooler chargepipes. In order for your car to stay legal it is vital that the car’s standard positive crankcase ventilation (PCV) system works as the factory intended. This occurs on all engines, but is worse on turbo engines due to the stronger combustion. "Hi Jim, sorry for the delay in getting back to you with this. I actually have noticed the difference, for the good. In reply, I've attached the email sent to me by Cam from TopSecret.