I cleaned a plastic pcv and a "HEMI" valve cover breather with carb cleaner last summer for my Duster. I pulled them off a set valve covers my father used to have on his car. They both had been sitting for a couple years and I had to put a lot of cleaner through the breather filter to get it clean (the pcv didnt take much). The pcv actually has a Pentastar logo on it. Any way, they are still functioning fine.