Running out of DEF

I ran out of diesel exhaust fluid yesterday. The dash display screamed at me constantly,until I could find a truck stop to by a 2.5 gallons of the nasty stuff. It automatically downgraded the truck to 55mph!

We didn't have to listen to that horrible noise for long, as there was a small truck stop on the corner. A box of the DEF cost about $22.50. That makes it about $9/gallon!! I usually purchase the stuff at the pump for $2.79/gallon. I will never make that mistake again. The DEF take holds about 20 gallons. As to the mileage range, I will have to get back to you on that.