My 2009 Cayman was idling rougher and getting smokier than usual at startup. Both telltale signs of a worn air/oil separator. Here's how I replaced it in my home garage. While this applies to both Caymans and Boxsters, note that this AOS is an updated design that's different from the 987.1 units.

I'm not a professional mechanic and this video is just intended to show how I approached this project. Use this information at your own risk. OK, disclaimer over. Be safe and enjoy!