DEF Urea crystals (snow)
 

Searched but did not find any discussion on this. Sorry if I missed a thread. Feel free to point me to it.
Is there a real concern about crystals? Service guy told me do not use DEF from a previous open jug. That urea crystals will ruin system. I can see being cautious about making sure to clean them off filler tube, but seems any residual would simply redisolve. Is my thinking flawed?

I just read a tsb that the crystals will turn back to a liquid when they are mixed back in. The tsb is listed in this sight.

Could not find it here so found it on another site here is a link it's clear at the bottom. https://dl.dropboxusercontent.com/co...GRHi/file?dl=1