I too feel the Iron is high, considering I also have magnets on the oil filter cap, and there was some residue on them. This truck no longer has the cat/dpf, and did not regen during the last OCI. It does make ~490HP/1070tq to the wheels, and is driven responsibly. I do tow with it, and pulled 13,500# and 8000# trailers during this OCI. Due to the future mileage this truck will see, all oil changes will be at the 5000mi mark. That is about a year of service on the oil, so no TBN for now.