Brown’s Fuels is a locally owned and operated business that has been delivering fuels to commercial and residential customers for years. We offer Diesel Exhaust Fluid (DEF) in a variety of formats to help serve you better. 

The History of DEF

DEF is a solution consisting of high purity urea and deionized water. It is the operating fluid required in vehicles that use Selective Catalytic Reduction (SCR) technology. In 2010, SCR was mandated in diesel engines as an environmental initiative. Engineers developed the emission standards to reduce nitrogen oxide (NOx) exhaust emissions from diesel engines. SCR can break down those emissions once DEF gets sprayed into the exhaust stream.

SCR has been around for nearly half a century and it was first used in the power generation industry to reduce oxides of nitrogen from coal-fired power plants. SCR technology achieves the reduction of exhaust fume emissions required and allows for maximum engine operation in terms of performance and fuel economy.

The fluid is contained in a designated DEF tank and it is sprayed into the exhaust system before the catalytic converter breaks down NOx into harmless nitrogen and water vapors.

The use of DEF API is the most effective way to take full advantage of SCR technology and to protect engine systems from the possibility of gradual degradation or clogging due to contamination. It also helps to prevent the loss of efficiency, costly parts replacement and engine downtime.


Frequently Asked Questions About DEF

What is DEF?

DEF is a mixture of high purity urea (32.5%) and water (67.5%). It is used to chemically reduce the concentration of nitrogen oxide (NOx) in the exhaust emissions from diesel engines. 

How Does DEF Work and How Should It Be Used?

DEF works through a process called Selective Catalytic Reduction (SCR). SCR uses a catalyst system containing ammonia to break down Nitric oxide (NOx) emissions. SCR can break down those emissions once DEF gets sprayed into the exhaust stream.

DEF is contained in a designated DEF tank on the vehicle. Never fill the diesel fuel tank with DEF or try to use it as a fuel additive.

How much DEF Do I Need?

DEF does not have to be replenished every time the diesel fuel tank is being filled.

The required amount is about 3% of the vehicle’s diesel fuel consumption, i.e. For every 100 gallons of diesel fuel consumed, only 3 gallons of DEF is required.

How Often Does DEF Have to Be Refilled?

For typical trucks and SUVs, a tank of DEF needs to be refilled about as often as changing your oil. For semi-trucks, refill is required a lot more frequently due to the mileage on your truck.

How Much DEF Will My Vehicle Consume?

DEF consumption is usually measured in terms of the amount of “dose rate” of diesel your vehicle consumes. Therefore, if you are driving a long distance or use your vehicle often, you will use much more DEF than someone who works locally. Usually, they say that DEF tanks are to be refilled every 4,000 to 10,000 km, but that depends on the size of the vehicle and its use.

How Will I Know if I’m Low On DEF?

Similar to when you are low on gas, you’ll know when you are low on DEF. All engines designed with SCR also come equipped with a gauge to display the DEF fuel levels. If you run out of DEF, lights will flash to notify you. Unlike gas, if you run out of DEF, it won’t impact the functioning of your vehicle.

Is DEF dangerous?

DEF is non-toxic, stable, odourless and colourless. If it gets on your skin or clothes, rinse with water. If in eyes, flush with clean water for at least 15 minutes. Although DEF is colourless, avoid spilling on clothing or vehicle upholstery.

What makes DEF API Certified?

Heavy-duty vehicle manufacturers demand a high level of purity for DEF to honour the warranty they give on their vehicles. DEF is a quality fluid that is API certified and meets ISO 22241 to ensure its purity and composition. It is delivered in dedicated, sealed DEF containers for protection from contamination, to help prevent damage to the vehicle’s catalyst.

How should DEF be stored?

DEF should be stored in a cool, dry, well-ventilated area at a constant temperature. For optimal shelf life (12 months), store between 86°F/30°C and 12°F/-11°C. It is better to keep DEF indoors, but an outdoor heated enclosure/container is also suitable. Avoid storing in direct sunlight. DEF will freeze at 12°F/-11°C. However, frozen fluid can be thawed and used without concerns of product degradation.

Does DEF Freeze During Cold Weather?

DEF freezes at -11 degrees Celsius, which is bound to happen in our Canadian winters! Typically, DEF thaws on its own from the heat of the engine and does not impact the functioning of the vehicle. Upon starting the vehicle, the SCR system provides heat to DEF tank, where it begins to thaw. As with any water-based fluid, DEF expands when it is frozen. Before shutting down the vehicle, wait a minute prior to turning off the battery. This delay will allow the fluid to drain out of the hoses and into the DEF tank.


What Are the Benefits Of DEF?

  • Reduced pollution- The main reason selective catalytic reduction was introduced was to help the environment. Diesel has been known to emit poisonous NOx emissions, typically blamed for causing acid rain and the greenhouse effect. With DEF turning the emissions into nitrogen and water, this is much more environmentally friendly.
  • Reduced maintenance- Engines designed with SCR technology have less wear and tear on their vehicles than those without, reducing the need for maintenance. Reduced maintenance also means that your vehicle is less likely to break down.

 To find out more about what DEF sizes we offer, give us a call at 1.888.542.7799.