I've asked this question before, but never got a solid answer. I know that just because an oil turns dark doesn't mean that isn't not performing properly. The flip side is if I'm running known quality oils (i.e. Pennzoil Platinum or Valvoline Maxlife) and the oil stays "clean," is that an indication that the engine is deposit free or that the oil is still performing? To simplify, has anyone documented a bad UOA on oil that still appeared essentially new? Note: I'd post a picture for fun, but have not figured out the trick on this forum yet.