When using DEF in extreme winter conditions, there are precautions to take before it becomes a “slush” and freezes into a solid state. Although, the quality or performance of DEF is not compromised if it freezes.

1. Activate and Test Heaters. However, don’t overheat the fluid. If able, set the thermostat to 40-45F.

2. DEF Not Dispensing in Cold Conditions. Dip the dispensing nozzle in clean water water – this allows urea to dissolve and dispense into the truck tank.

3. Top-Off Tanks in Extreme Winter Conditions: DEF freezes more easily in small volumes compared large volumes – leave 7% head space for expansion.

4. Do Not Add Anti-Gel Agent or Freeze Inhibitors: Agents & inhibitors can impede DEF’s function to remove NOx and can also damage the SCR system.

5. Bring it Indoors: There’s no harm to the quality or performance if DEF freezes, but it can be annoying.