I figure about 3000-3500 miles per tanks of DEF. Maybe more but we'll see. I buy Blue Peak about 11$ per 2.5 gal cube.

The GM's aren't programmed to require more DEF @ oil change intervals. However, depending on use, conditions, and distance between changes you could need fluid.

There were some early programming issues and there were problems with topping off between oil changes …the system didn't "see" the top off etc etc. but the system isn't designed to use "x" amount of DEF per mile so the dealer can sell more DEF fluid.

If you top off too frequently the system doesn't learn how much you're using, which is one of the reasons the recommended interval is at your oil change.

its cheaper if you buy at the truck def station .. just pump it in .. like 2.00 gallon

Picking up my new 2500hd Ltz duramax this Monday . It's been 14 years since my last duramax. I got my first there first your in 2001. Loved it and I'm still not selling it. On Tuesday the new one goes in for 3" skyjacker kit. This one I'm getting is crew cab short bed my old one was extended cab long bed. So although still long I can fit the fam

Buy it at the big truck stop from the pump for sure. No mess, no trying to balance a 2-1/2 gallon container at arms length over the fender on a lifted truck. And you're not guessing when it's full and making a mess because the pump has the auto shut off feature.

At the pump in Charlotte, empty (under 100 miles to go per the dash computer) to completely full for around $17. Cheaper for sure but saving the 5 bucks difference is whatever. It's just way easier.

I hate to go to truck stops. They do not have the best food despite the rumors.

I added the same grill insert for the trans cooler. Looks great. My truck has 6000 miles. 1 time I've had the low def fluid light on and 1 oil change also. The def fluid did not make it to the oil change but it was also topped off when the oil was changed.

no but the def surly is worth stopping buy lol

Got it ltz z71 loaded. It's nicer than my wife's bmw. And that bawls to back it up. Very happy with my purchase even if it was 55k. Lol

I'm really struggling on whether to get a 2500 Duramax 4x4 or a 6 liter gasser Denali 4x4. I'm having a hard time justifying the Duramax at about 10% towing miles, and now with a lighter boat to tow on long trips.

I got the wife a 15 Yukon Denali last year and it is just bad a$$.

Congrats on the new ride...