I have been reading about attaching a catch can to the 998 because some people found that the air box had oil in it. Is this a real issue? Some suggest that you not fill the oil tank to the full mark as this prevents the blow by. The posts that showed up in my search were rather old and I do not know if they are still valid. I just brought mine in for the 7500Km service and they replaced the air filter but did not mention anything about it being oily.