Yeah, I guess the correlation is obvious, I obviously need to proof my posts...
. But what I'm really wondering how heater placement & output could impact it. Because whether it's two gallons or 5, at those temps it's going to be frozen after a few hours. My car sat outside as temps dipped into the -30f territory overnight, which would suggest, based on the composition of AdBlue, that the tank contents should be "frozen solid".
I haven't found the tank/system diagram to see where and what type of heater(s) are being used.
Like you I tend to keep the same fluids full for the same reason. This issue is curious to me though, because it seems so intermittent... As a self proclaimed gearhead, and degreed engineer, I would like to understand it from a 5-why, Root Cause standpoint.