DEF (urea) isn't too bad, it's the damn DPF that screws mileage up. The last 2.5 gallon jug of DEF I bought was less than $11 at Sam's and will last about 5,000 miles. Hard to complain about an extra $11 every 5,000 miles.
Now the DPF and the 2-3 gallons of fuel wasted every regen cycle (250-500 miles) are another matter. The DPF also restricts exhaust flow, hurting mileage.
Last edited by K1500; 12/26/12.
