Kinda funny that most of them on Amazon are listed under wireless phone accessories!The purpose of the oil catcher is to prevent a runaway if you start too get too much oil vapor in the block. The engine can run on the fumes even if the fuel is shutoff. I bought this one from amazon. It was under $20. Amazon.com: Engine Oil Separator Catch Can Reservoir Tank - Baffled with Inner Filter for Pcv Valve - Barb Adapter 10mm: Car Electronics