Guys,
My buddy Darren owns a very large excavation company with over 60 diesel engines in his fleet. At any given time more than 50% of his fleet have in excess of 10,000 hours on them. He uses no fuel additives what so ever. He has had numerous un-rebuilt Cummins, Cats, Deere's, Yanmars and Kubotoa engines all exceed 20,000 hours. One of his employees, his lead mechanic, used to work as a diesel mechanic on outpost generators in Alaska, the same Cat, Cummins etc. engines we use in boats powering small towns or outposts. These engines run 24/7/365 and they also don't use any fuel additives. It's always good for me to pick their brains when I am over-thinking marine engines that barely see a few hundred hours per year..