Mobile 1 is excellent oil, but after comparing it extensively to oils like Mobil 7500 or Motorcraft syn blend 5-20, there's not enough of a difference to justify the price difference. If price of oil wasn't a concern, I'd be running royal purple. I also change it at 5,000 miles, but that's just me. Again, my suggestion is Motorcraft 5-20 every 5,000 miles. Ford doesn't recommend using any other additive either.
