PCV valve clogging

I have a 93 Metro, 1L 5 speed 127,000 miles It runs great (45mpg) with the exception that the pcv valves clogs up and then it leaks oil. Clean the pcv valve and its fine for a couple weeks. I put in a new pcv valve yesterday, I kinda dont think thats gonna solve the problem. Whats causing it the pcv to clog with some yellowish goo?
Thanks!

sounds like engine is either tired and its using some oil or someone didn't change oil often enough before and its sludged up. not sure about yellow color though unless its using some water