Originally Posted by Jason911
Once it drops down - don't ever fill it full again. It's much easier to manage the usage when the gauge reads ¾ or less - at least from my personal experience.
I concur. Given that I use about 1 tank per year, I am planning to keep mine between 25 and 50% from now on to reduce the average age of the DEF in my tank.
Also, given that this isn't fact in the manual, I feel compelled to mention in these threads that due to the weird ultrasonic sensor, it is important to always add at least 1 gallon
when refilling the DEF tank.