DEF volume for low use vehicle?

[Thorny]

I only plan on driving my CTD powered 2500 around 12k miles a year. Not sure how many miles one can get from a tank of DEF, but I have read about it going bad over time. So I’m wondering if I should run the def tank from 1/2-0 then refill with a couple gallons, or if I should try to keep it full, knowing some of the fluid is going to be quite old?

To add to the puzzle, I live in Colorado and winter temps will lead to condensation in the tank and freezing as well

 

[Jimmy07]

I only plan on driving my CTD powered 2500 around 12k miles a year. Not sure how many miles one can get from a tank of DEF, but I have read about it going bad over time. So I’m wondering if I should run the def tank from 1/2-0 then refill with a couple gallons, or if I should try to keep it full, knowing some of the fluid is going to be quite old?

To add to the puzzle, I live in Colorado and winter temps will lead to condensation in the tank and freezing as well

Just throw in about 2 gallons each time you need it. There’s a heater in the tank and it looks like a bunch of tendons that reach various spots and levels of the fluid.

 

[crash68]

^^^ what he said
DEF usage depends on how much fuel your burning. Typically you'll go through 1-2% of the amount of fuel used. When your you go through a lot more DEF than driving, carry extra with you.