DEF tank level

[KBob]

I'm reading for the first time, "filling the DEF tank to the brim is not advised". Is this because of freezing weather causing problems when it freezes , and making it harder for the tank heater to do it's job? I've had my 2020 for almost a year now, and in the summer I always filled it with no issues. As it so happened I was at 2/3 tank during the recent below zero weather, and my truck rested in the garage on a trickle charger for the whole event. Warm weather is back, and everything seems fine. Planning a long trip in a 6 weeks after freezing weather is over, and was getting ready to top off with a fresh box. Thoughts?

 

[Bozo]

Wait til it is closer to 1/4 or less. I personally add at diesel stops via def pump and never top off to full.

 

[yycdiesel]

If you have cold weather like us in Canada I advise you to fill before going past half full, two times now I missed it and the gauge didn't register until I was almost in limp mode.

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[KBob]

Wait til it is closer to 1/4 or less. I personally add at diesel stops via def pump and never top off to full.

You say wait, and clearly I can do that, but my question is how Full is Too Full? and Why?

 

[KBob]

If you have cold weather like us in Canada I advise you to fill before going past half full, two times now I missed it and the gauge didn't register until I was almost in limp mode.

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What I have figured out is the computer looks at your current MPG, and calculates how long it will take to drain the tank. If you are singing down the highway with a tail wind getting 25 mpg (mine will do that! Woot...) you can probably run it down lower, but if you are towing into a headwind and only getting 8 mpg it calculates it's going dry much sooner, and the warning pops up early. At least That's what I "Think"

 

[H3LZSN1P3R]

If you have cold weather like us in Canada I advise you to fill before going past half full, two times now I missed it and the gauge didn't register until I was almost in limp mode.

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Thats odd i just wait for the light never had an issue yet im up here in northern Ontario... i also noticed when its really cold my def ussage drops significantly im assuming because its frozen and running without it

 

[Bozo]

You say wait, and clearly I can do that, but my question is how Full is Too Full? and Why?

Point is, if adding from a jug, wait because the chances of over filling and spilling are likely given the gauge inaccuracy. Also it is easier to just add it from the pump when I fuel up. I filled via jug twice before I gave up and just do it at the pump now. Way more convenient And I can keep it fresher, at least I think so. My years of truck driving got me into the habit, I trusted the def gauge one too many times and had a Derate (semi) on the interstate and had to limp to an exit and have a coworker bring me a jug. If you like, just carry a jug if you get nervous about going under half tank full mark.

 

[H3LZSN1P3R]

Point is, if adding from a jug, wait because the chances of over filling and spilling are likely given the gauge inaccuracy. Also it is easier to just add it from the pump when I fuel up. I filled via jug twice before I gave up and just do it at the pump now. Way more convenient And I can keep it fresher, at least I think so. My years of truck driving got me into the habit, I trusted the def gauge one too many times and had a Derate (semi) on the interstate and had to limp to an exit and have a coworker bring me a jug. If you like, just carry a jug if you get nervous about going under half tank full mark.

I just fill it one jug at a time for that reason and have a spare if im hauling heavy far

 

[Bozo]

I just fill it one jug at a time for that reason and have a spare if im hauling heavy far

Yep! After that incident, I always carried a jug.