[Javi]

In the 6 years I've owned the F350 my DEF usage is an average of 3200 miles to 2-1/2 gallons of DEF... Generally if I tow a lot in the period the mileage is a little less..

I normally fill mine up within 500 miles of when I first see the LESS THAN 1/2 warning and it will take the whole 2 1/2 gallons if I fill at the first flash of the warning I can't get the full jug in the tank... hence the wait.