What metal rocker clips? No, the oil is whatever you like to run. 20/50, in my opinion, is not for a street car, although lots of guys run it. Yes, it might quiet things down some, but if you have a problem, do you just want it to be quiet, or do you want to find it? The 10/30 is fine, and I always run regular oil...synthetic is OK too, but too pricey for what you get. I change mine quite a bit anyway. Yes, replace the spring in dist, and try it again...it could be a timing issue. But it sounds like cam/lifters/springs to me. Try it and let us know. John