Have you ever been at a quick lube/oil change place and the technician comes walking up to you holding a little metal device which he/she calls a PCV Valve, then tries to sell you a new one for $10?

 

Positive Crankcase Ventilation Valve - If they found it, then yes, you probably have one.  It should be replaced about every 12,000 miles or so.  What does it do?  Keeping it simple, it affects your gas mileage and emissions.  Always refer to M.O.M. (Manufactures Owner's Manual) to find out if and when it should be replaced.  Also, not all vehicles have a replaceable PCV Valve, which is another reason to consult MOM.

 

And, yes, it's a good idea to invest the $10 to get a new one; only if MOM says you're due.