Thought some of us diesel guys could share our usage of the Urea! Sounds like a venereal disease! My truck, 2012 Ford Super Duty, 6.7 Power Stroke. Got 5708 miles before the warning popped up. Had the truck serviced and they supposedly topped off the DEF. 1100 miles later got the 500 mile warning again. All 1100 miles had been towing my 6 X 10 trailer around to shows and work. Not sure of the weight, but the damn thing is almost overloaded. Bought 2, 2.5 gallon jugs of DEF and added one to the tank and that brought it full. So it was definitely topped off at 6800 miles. Post what you are going through please so we can compare. I know about the deletes but I don't have the cash to do the mods right now.