The PCV ( or PVC if you are a plumber ) valve is a must if you are driving on the street regularly. Your oil will stay cleaner and there will be less sludge / acid build up in your engine. Small oil leaks will often disappear. There are a million to choose from at the parts store, and if you have made ANY engine modifications at all, trust me, none will apply. The best you can do to see if your system is working is to check for crank case vacuum at idle ( piece of paper over the breather hole in the opposite valve cover, etc ). It's a guess at best. Well "ME Wagner" has taken the guess work out of PCV valves with their fully adjustable valve. It's a little pricey, but it's a really slick piece and the machining quality is a work of art. It can be used in two modes - fixed orifice ( idle circuit only ) or dual flow ( idle and cruise ). Instructions make it easy to set up. Now, any time you make cam, carb, head, intake change, you can dial in your PCV accordingly. Part # DF-17. www.mewagner.com No, I don't work for the company. This is not a sales pitch. It's a tech tip.