Well, I just started my first AutoRx cleaning phase. Main reason is car has developed an annoying ticking noise. Most likely lifter noise and has started to burn some oil. Not much (about 1/2 quart every 4-5k miles), but its been solid for its entire service life so far. I just hit 100k and thought why not. I maintain it well with regular OCI using synthetic oil since 30k miles. The black spots on top are puddles of oil, not deposits. I can't imagine AutoRx getting this any cleaner.