For my 1996 Contour Ford provided a "free" 60,000 mile change of the PCV. You had to do it within 500 miles of 60,000 miles either way for it to be free. It's a REAL pain in the butt to change it. I watched the mechanic do it. I didn't burn/use any oil before and none afterwards. Chances are I'll never change it again. I'm only at 78,000 miles. If you don't burn oil then I feel the PCV should remain clean.
Whimsey