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Discussion Starter #1
This past week, we took our Canyon from just North of St. Louis back to visit family in Ohio, an hour North of Colombus. The truck did great. The wife, son, myself, and our luggage packed in the cab of the truck, along with a makeshift shelter for our two dogs, one lab mix and one fox hound mix, and the sons Polaris 90 ATV in the bed of the truck (had to put the tailgate down to get it to fit). Round trip, plus the extra driving we did while at home, totaled 1350 miles. I had figured the first tank of fuel and it was getting about 26.6 (there was a pretty good head wind we drove into all the way home) while I think the truck said 27 or 27.5. Forgot to reset the trip so it accumulated all the miles of the trip, and by time we got home last night, it said the trip average was 28.0.

I was very impressed that on the way home, I fueled up about 10 miles from my parents house, then drove 510 miles back to my house, never filled up again and the estimator said I still had 115 miles until empty :cool:

One thing I did notice, and I'm not sure what it is that is causing this, but at times, especially when we were at home driving around after I had unloaded the atv, the truck started getting up to 35-40 mpg on the instant readout on level ground at 65-70 mph. It did this enough that I increased the best mpg avg to 34.8. I have two thoughts on this: that dog shelter I put in the back is level with the bed rails and as wide as the bed, and about 25 inches long. I didn't know if that thing changed the airflow going over the truck enough to get me those better mpg's or not.

My other thought though; If the truck was running a higher rate of DEF through the system, would that increase my MPG?

We were about 100 miles from home last night and I scrolled through all the info pages on the truck and came to the DEF page and it was at 29% and the oil filter life was around 58%. We did an oil change around 6,000-6,500 miles I believe as the oil filter life was around 20%. The DEF level had got down to about 20% at the same time, so I told my wife to make sure they filled that up when they did the first free maintenance. On the way home last night, we rolled over 10,000 miles on the truck. I don't know if they didn't fill the DEF up completely or perhaps the long trip sucked down the DEF, or maybe something is wrong and it is just using more?

One more note, as I think rockcrawler had mentioned something about his Transmission fluid getting hot on his truck, and he may have been pulling something, I don't remember. Yesterday, it was about 95 degrees for most of our 9 hour trip. The transmission was running about 186 degrees at the warmest on the highway. It did okay though.
 

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Nice mpgs, especially with crap in the bed.

As far as the def, I wouldn't say anything is wrong with your truck just yet. But, keep an eye on it. My def went from 26% to 13% on one 200 mile day trip while towing and then it took like two more weeks to get down to 10%. There is no way to tell if they filled it up all the way, but there is also no way to fill it all the way without overfilling it, so I bet they don't try to fill it all the way
 

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SO, a lot to cover here lol
1) the atv in the bed of the truck, added to the fact that the tailgate was down would have a relatively drastic impact on the aerodynamics of the truck when you are going 60-70 mph, that would explain why you got so much better mpg coming back,
2) if the truck was running a regen, you mpg would go down, not up. the only time your truck uses DEF is when it is burning extra fuel to reach a hotter temp. the higher temp creates NOX which mixes with the ammonia in the DEF to create carbon dioxide and water
3) as for your def levels, i would say that it probably had some fluid added, but wasnt topped off. the alternative is that it is using too much (which usually either comes from either excessive idling or some faulty equipment). i would like the be optimistic and assume they just didnt top it off.

we had a truck we serviced here that had put 223k miles in 1 year. he basically ran the truck non stop. when we checked his service records, he was goin almost 30k miles between topping the truck off with DEF, what im getting at, is that if you are driving the truck on long huals, unless you are at an awkward speed for the transmission, it shouldnt be going through a bunch of DEF
 

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That guy must have a good service plan, since he would need his oil changed every 10 days or so. Lol.

He must do hot shot delivery or something
 

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Gotcha. Yeah, it didn't do much idling so hopefully they just didn't fill it up completely.

And about the atv in the truck, I actually thought I got a little worse fuel economy with that in there and the tailgate down with the dog shelter, while I believe it got 5-10 mpg better with the atv unloaded, tailgate closed with the dog shelter still in place.
 

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In my experience they fill the DEF tank enough to clear the % readings. Once it says DEF level "ok" they stop. Penny pinching.
 

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You would certainly get better milage without the ATV's extra weight and worsened aerodynamics. With the dog shelter only it sounds like you practically had a bed cover which will definitely help boost fuel economy.

Gotcha. Yeah, it didn't do much idling so hopefully they just didn't fill it up completely.

And about the atv in the truck, I actually thought I got a little worse fuel economy with that in there and the tailgate down with the dog shelter, while I believe it got 5-10 mpg better with the atv unloaded, tailgate closed with the dog shelter still in place.
 
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