Question DEF testing?

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Joined
Nov 3, 2019
Messages
368
Location
Florida
RV Year
2018
RV Make
Newmar
RV Model
CanyonStar
RV Length
39' 11"
TOW/TOAD
Demco KarKaddy 460SS and VW Passat
Does anyone test the DEF in their DP? Or do you just follow a specific routine and hope for the best? Recently I came across someone complaining about their Newmar that they had just purchased from a dealer at a great discount, it was a 'new' left over, 2019 maybe or 2018. Been sitting on a desert dealer lot for who knows how long. They had check engine lights, limp mode etc during their first trip which was in my opinion very long for a newly acquired vehicle without so much as an extensive walk around from what I could gather. Some of the problems sounded like bad DEF which is possible if it sits in the hot sun too long, I hear. Does shelf life of DEF decrease dramatically with heat? I am researching diesel issues as I consider upgrading to a diesel.
 
Joined
Jul 27, 2019
Messages
3,378
Location
Midlothian, VA
RV Year
2017
RV Make
Newmar
RV Model
Ventana 4037
RV Length
40' 10"
TOW/TOAD
2017 Chevy Colorado
I do not test DEF but I also deliberately keep it fresh by running it to just below half (2 dots of 4 on my display) and go a bit after I'm down to 2 dots. I only fill DEF from truck stops for the same reason Diesel is preferred at truck stops, turn over and fresh. I don't know if there is a way to drain the tank, i.e. pull some plug from below but like fresh tanks it would be nice to dump it in the case of your scenario above and add fresh def. It could be a doser issue, something clogged up from crystalized DEF, who knows. Something for the chassis vendor to investigate.
 
Joined
Nov 15, 2019
Messages
240
Location
SW Florida
RV Year
2017
RV Make
Newmar
RV Model
Ventana 4369
RV Length
43
TOW/TOAD
24' Enclosed (Mini & Harley)
I sit in SW Florida for anywhere from 4 to 5 months during the winter. I usually get one "exercise" drive in but otherwise 99% of my DEF is sitting in the heat unused. I'm guess that for DEF to age out while actually in the tank it would have to sit for a year or more.

Based on recent experience, now every time I hear of issues with a newer DEF tank causing issues I suspect a faulty DEF header. According to North Trail these DEF headers have been failing more than usual.
 
Joined
Nov 4, 2019
Messages
557
Location
No Where In Particular
RV Year
2020
RV Make
Newmar
RV Model
Dutch Star 4369
RV Length
43’ 9”
TOW/TOAD
2016 Colorado
During Alaska trip and the need to buy DEF in stores I did test with a refactor I had purchased at the suggestion of someone. Usually in lower 48 I always buy bulk at stations and don’t test.
 
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