AdBlue in winter – how to prepare for freezing temperatures
AdBlue freezes at approximately –11 °C. What does that mean for the SCR system during the Finnish winter? Read about how you should prepare for periods of severe cold and what alternative Defrosta offers for demanding winter conditions.
Finland’s winter puts a real strain on heavy-duty vehicle SCR and AdBlue systems. The freezing point of AdBlue is around –11 °C (12°F), so during winter, temperatures often drop well below this threshold.
Vehicle SCR systems are designed to account for AdBlue freezing, but extended cold spells, large tanks, and fleets that are continuously outdoors can make winter operation challenging.
That’s why it pays to prepare your SCR system for winter as early as fall—before the first hard freeze.
What happens to AdBlue in freezing temperatures?
AdBlue is a urea solution in line with ISO 22241, used in diesel engine SCR systems to reduce nitrogen oxide emissions.
AdBlue freezes at approximately –11 °C (12°F). This freezing has been accounted for in most heavy vehicle SCR system designs, and the systems use heaters to thaw frozen fluid.
However, in harsh winter conditions, prolonged sub-zero spells can put extra stress on SCR systems. This is particularly true for equipment parked outdoors for long periods, or that uses large AdBlue tanks.
Freezing isn’t the only winter challenge
SCR systems can also suffer from urea crystallization and deposits.
Crystallization can occur in the dosing system or other parts of the SCR system. In the worst case, such issues can cause error codes, an increased need for maintenance, and unplanned downtime.
In commercial use, reliability is key: trucks, buses, and machinery need to stay up and running even when the temperature dips below –20 °C (–4°F).
Start preparing for winter already in the fall
It’s important to check your SCR system before the freezing season. Before winter, you should check for example:
- that there are no error messages in the SCR or AdBlue system
- the overall functionality of the system
- any leaks or visible crystallization
- the cleanliness of the fluid in use and proper storage
- the temperatures and operating conditions your equipment will face during the winter.
Heavy vehicles and machines that remain outdoors may have to work for extended periods at temperatures far below AdBlue’s approximately –11 °C (12°F) freezing point.
Defrosta® is developed for demanding winter conditions
Defrosta® is a urea-based additive for SCR systems, manufactured in Finland. Its purpose is to improve an SCR system’s resistance to freezing and operational reliability in cold conditions.
Defrosta’s technical freezing point is around –30 °C (–22°F).
If necessary, Defrosta can be used mixed with AdBlue. The technical freezing point of the mixture will vary depending on the proportion of Defrosta used.
| AdBlue | Defrosta | Technical freezing point |
|---|---|---|
| 100 % | 0 % | –11 °C |
| 75 % | 25 % | –15 °C |
| 50 % | 50 % | –22 °C |
| 25 % | 75 % | –25 °C |
| 0 % | 100 % | –30 °C |
Note: The mixing ratios in the table refer to technical freezing points, not to usage or mixing instructions.
Defrosta is designed for professional use.
Important: Defrosta is not AdBlue
AdBlue is manufactured according to ISO 22241. By contrast, Defrosta is a separate urea-based additive whose purpose is to boost an SCR system’s cold resistance and operational reliability in low temperatures.
Defrosta acts as a urea-based agent in SCR systems and can, if required, be mixed with AdBlue.
The difference between the products is essential, especially when it comes to vehicle manufacturer instructions and warranty terms.
Consider the vehicle’s factory warranty
Vehicle manufacturer warranties may be voided if AdBlue is completely replaced with Defrosta or if fluids not approved by the OEM are used in the system.
Defrosta does not yet have official approval from vehicle manufacturers.
For this reason, Defrosta is intended primarily for professional use where system reliability in demanding conditions is critical and decisions on its use are made considering the bigger picture.
Always check your vehicle or machine’s operating instructions and warranty terms before using this product.
Also consider AdBlue system sensors
Some vehicles have a sensor in the AdBlue tank that measures urea concentration.
In such vehicles, using Defrosta can trigger error codes since the composition of the blend differs from standardized AdBlue.
It’s important to clarify this in advance, especially with newer vehicles and machinery.
Who is Defrosta intended for?
Defrosta is designed for professional use, especially in conditions where equipment reliability in harsh cold is essential.
Typical applications include:
- heavy trucks and buses
- delivery vehicles and other utility vehicles with SCR systems
- off-road vehicles and construction machinery
- marine and industrial SCR applications.
Suitability for your equipment must always be evaluated based on your vehicle’s or machine’s manufacturer instructions, the system’s design, and any possible warranty or sensor limitations.
Prepare for winter before the first big freeze
Think about your SCR system’s winter operation while temperatures are still positive in the fall—not only once the first cold snap hits.
Checking the condition of your system and evaluating your equipment’s winter operating conditions in advance will help you avoid surprises in the busiest period of winter.
Under especially tough cold conditions, Defrosta is an option for boosting the cold resistance and functionality of your SCR system.
Check out Defrosta products in the Proxel.fi webstore:
- Defrosta® SCR additive 200 L – technical freezing point approx. –30 °C
- Defrosta® SCR additive 1000 L IBC – technical freezing point approx. –30 °C
Want to learn more? Also read our article Defrosta – a Finnish solution for SCR system winter operation.