FYI, Volvos have used flametraps since at least the 70s, maybe before and it was never an afterthought. It was Volvos version of what almost every other car company substitutes another similar device called a PCV valve.
Checking flametraps is suppose to be done every 30K miles by Volvos service manuals but is often overlooked by those who don't know about that. Any experienced Volvo technician or experienced mechanic anywhere for that matter should know about PCV systems whether it's a flametrap or PCV valve, especially if the engine's blowing oil from seals and/or its oil fill cap.