6 Tips for Using & Storing DEF During Cold Winters

When it comes to Diesel Exhaust Fluid (DEF) in cold weather, there are several key considerations to keep DEF effective and prevent issues with your construction equipment. Here are some things to keep in mind:

1. Freezing Point: DEF begins to freeze at around 12°F (-11°C), so if the ambient temperature is near or below this threshold, it will likely impact machine performance. Most modern heavy equipment includes heating elements to keep DEF from freezing while the machines are in operation. If your machines aren’t equipped with these features, you’ll want to monitor them more closely before operation.
2. Storage: DEF should be stored in temperatures between 12°F (-11°C) and 86°F (30°C) for optimal longevity. If it freezes in storage or in the machine’s tank, it can be thawed without losing its effectiveness. Just make sure to allow it to return to its liquid state naturally — never apply excessive heat or other additives to thaw DEF.
3. Expansion in Tanks: DEF expands as it freezes, so be cautious about filling tanks completely during cold months. If your machines stay out in the elements (especially overnight), leave some space in the tank to prevent cracking and accidental damage. And again, if DEF freezes in the tank, it’s best to let it thaw naturally.
4. Quality Checks: Cold weather can reduce the lifespan of DEF if it’s exposed to extreme conditions during storage, so check the fluid for clarity. Any discoloration can indicate that it’s no longer pure, potentially causing issues with the Selective Catalytic Reduction (SCR) system. When DEF gets too cold, it can turn a milky or cloudy white color — that’s what you should look for. The discoloration is typically due to the formation of urea crystals. Once it warms back up and the crystals dissolve, the DEF should return to its original clear or slightly blue tint if it hasn’t degraded. However, if it remains cloudy or off-color after warming, just be aware it may indicate contamination or quality issues.
5. Handling and Dispensing: In cold weather, using insulated dispensing systems can help maintain DEF in a liquid state and avoid line blockages. This is especially useful for refills on-site. On new Volvo excavators, we’ve also added new DEF sight gauges and a splash guard to help prevent inadvertently putting DEF in the diesel tank and DEF contamination.
6. Additional Precautions: When not in use, park your equipment in heated areas, if possible — this keeps both the equipment and DEF ready to operate without delays from freezing.

These steps can help prevent DEF issues in cold conditions, keeping your equipment in good working condition throughout the winter months. And be sure to check out this article that includes top tips for avoiding common problems with diesel exhaust fluid.