Truck drinks DEF, but I tow a lot so I guess that's to be expected. 8500 miles on the truck, and 4 jugs of DEF so far. Had the first oil change, and about 600 miles later the 30% DEF comes on.. Guess the dealer didn't fill it. Oh, and why the refill under the hood? No way my wife can reach up to do that. Truck hauls like a beast though, and I do know the top speed.