mechmike10
Advanced Member
We have a 2016 SPrinter Sportsmobile. It has steering wheel menu controls (we ordered that from MB when we bought the van). There is a DEF gauge in the menu system. I find that when it reads 1/4 tank low, it will take 1 gallon without overflowing. Our salesman told us that it is their recommendation to keep the tank topped up because it reduces the amount of air in the tank, which in turn reduces the the amount of DEF that sort of evaporates out and turns to a white crusty substance. I have generally followed that advice. When we are on the road, when I notice the level getting near or below the 3/4 full level, I try to stop at a Wal Mart for a gallon, which i put in ASAP and then dispose of the bottle. I try to avoid transporting DEF in the van for any distance because it is so corrosive. At home, I'll buy the larger 2 1/2 gallon bottle and add it as needed since I don't mind storing that in my garage.