I`ve learned the hard way about doing things myself. My motor was fine at 197k , burning only a half quart of oil evey 3k miles. I got an oil change done at a shop and the clown didn`t tighten the drain plug all the way. When I got home, I had one and a half quarts left. Now my valve guide seals are gone and I burn half a quart of oil a week. All we can do with used cars is fix things other people messed up.