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Insight Horizon Media

How do you winterize a DEF fluid?

Author

Mia Smith

Published Feb 25, 2026

How do you winterize a DEF fluid?

Push the DEF pump switch to “Trailer Fill”. Allow the pump to run while squeezing the nozzle handle for 30 seconds. Unhook the quick coupler from the nozzle WHILE THE PUMP IS RUNNING. This will evacuate the DEF fluid from the nozzle.

Will DEF freeze solid?

“DEF will begin to ‘slush’ before it freezes and will ultimately freeze into a solid state when the fluid temperature reaches 12 degrees F,” Kladder says. “However, the process of freezing DEF has no effects on its quality or performance.”

Does DEF go bad if frozen?

DEF isn’t harmed by freezing, good news for those who live in colder climates. Because it’s 2/3 water, it begins to turn slushy at 12 degrees Fahrenheit and will freeze solid. One thing to keep in mind is DEF will expand when frozen, so it’s best not to fill containers completely full to avoid damage to them.

Can DEF be stored outside?

Keep DEF out of direct sunlight. If DEF is stored outside it must be kept shaded from the sun. DEF will begin to lose its urea potency if kept in direct sunlight for too long. Store DEF below 86°F (30°C) or in the coolest part of the storage facility.

How do you keep DEF from freezing?

Preventing Frozen DEF Storing your truck in a heated or insulated garage during cold periods can help prevent your DEF from freezing. Likewise, an insulated tote blanket can help prevent freezing. More details about your truck’s specific after-treatment system can be found in TruckSeries.

Does DEF freeze in the winter?

Handling and storing DEF in cold climates can be challenging. Made from a mixture of technically pure urea and purified water, DEF freezes at 11 degrees Fahrenheit and needs to be properly maintained and dispensed to preserve its quality.

What temp does diesel freeze?

32 degrees Fahrenheit
It’s right at the freezing mark, 32 degrees Fahrenheit, that the paraffin in diesel fuel begins to stiffen, leaving the fuel tank clouded.

Does DEF freeze?

Diesel Exhaust Fluid or DEF Fluid Whether in storage tanks or in equipment, DEF can freeze and possibly cause issues. As temperatures drop below 12°F, DEF will begin to solidify and not work as intended.

Can you store DEF in the cold?

Handling and storing DEF in cold climates can be challenging. Made from a mixture of technically pure urea and purified water, DEF freezes at 11 degrees Fahrenheit and needs to be properly maintained and dispensed to preserve its quality. Keeping a tank that you think may freeze less than full is a good idea.

What temp does Blue DEF freeze?

11 degrees Fahrenheit
Handling and storing DEF in cold climates can be challenging. Made from a mixture of technically pure urea and purified water, DEF freezes at 11 degrees Fahrenheit and needs to be properly maintained and dispensed to preserve its quality.

How do I stop my truck from freezing in DEF?

Storing your truck in a heated or insulated garage during cold periods can help prevent your DEF from freezing. Likewise, an insulated tote blanket can help prevent freezing. More details about your truck’s specific after-treatment system can be found in TruckSeries.

Can I use DEF that has frozen?

Like water, DEF will expand up to seven percent when frozen and can damage a truck’s DEF-storage tank if it is full or nearly full when it freezes. If DEF freezes in the vehicle, do not put any additives in the tank to help it melt. The fluid needs to remain pure for it to work correctly.