I would like to run regular unleaded in my recently purchased 2000 Navigator. I have a 1998 Navigator which I've ran 87 octane in since I've owned it with no problems so far. I know the 2000 has a higher horsepower rating and was concerned about any engine damage I might incur from running a lower octane gas than what is recommended by the manufacturer. I believe the 2000 still has a knock sensor and engine computer management to handle the octane situation, but want to be sure before changing over.
Not necessarily the case. My '97 Mark VIII ran well ONLY on 92 octane or higher which was [u: af821e28d0]recommended[/u: af821e28d0] in the owner's manual. It wouldn't run right if I used 87 or 89 octane. And a '95 Continental I owned was premium fuel ONLY (not just recommended, but [u: af821e28d0]required[/u: af821e28d0]!).
I've been thinking about running 89 octane in my '98 5.4L Expedition. Haven't decided yet.