Good question, no idea
. They're cheap, and I'm at 30K miles. I just put in an order for a pair of them from courtesyparts because, hey, why not.
Edit: parts list from the order (2x rubber O-rings, left/right PCV valves):
2 x [11812] RUBBER PCV,VALVE - 370Z (Z34) 2009+ (11812-Z34001) = $4.92
1 x [11810PA] VALVE ASSY-CONTROL - 370Z (Z34) 2009+ (11810-Z34004) = $14.57
1 x [11810P] PCV VALVE - 370Z (Z34) 2009+ (11810-Z34003) = $14.57