re: What percentage of people routinely change their oil?

Ok, I knew a guy that believed an article he read and never changed oil, only added when necessary. He called me one Sunday and said his car sounded funny and his oil looked real dark. It was back in the early 90s. I heard a squealing under the valve cover. It was an in line 6 Nissan. It was packed with crud under there. We cleaned it out and changed oil and filter and he became a believer in oil changes afterwards.