Keeping DEF in spec on the yard
DEF is not a fuel. It is a urea solution that SCR systems need clean. Storage decides whether it stays usable.
Heat and sun shorten its life
DEF breaks down faster when it sits hot. Keep totes and tanks out of direct sun and away from heat sources when you can.
Ask your supplier for the storage temperature range and shelf life printed for their product, and rotate stock so the oldest goes out first.
Cold is a different problem
DEF freezes in hard cold. Freezing does not ruin it, but a frozen tote cannot be pumped. Heated storage or indoor placement helps on winter yards.
Keep it clean
Small amounts of dirt, fuel, or tap water can contaminate DEF. Use dedicated pumps, hoses, and nozzles that never touch diesel.
Keep caps on and fill from sealed containers or a supplier delivery, not from reused jugs.
Questions
Can DEF come on the same truck as diesel?
Some distributors carry DEF with fuel. Check the DEF badge on the profile.
Does frozen DEF go bad?
Freezing alone does not spoil it. Let it thaw before use.