Answering Your Frequently Asked Questions About Diesel Exhaust Fluid

Answering Your Frequently Asked Questions About Diesel Exhaust Fluid

Even though the laws mandating Diesel Exhaust Fluid (DEF) are several years old at this point, there is still some confusion regarding the fluid and its usage.  In particular, buyers often have questions if it’s their first time buying a vehicle with a Selective Catalytic Reduction (SCR) system, the necessary component for using DEF.

So, our team at Bird Fuels wanted to quickly cover some of the questions we most frequently hear about DEF.

Get the FAQs About Diesel Exhaust Fluid

What is DEF, exactly?

DEF is actually a very simple substance: 32.5% urea, and 67.5% ionized water.  Urea, incidentally, is a naturally occurring compound most commonly found in mammal urine and is noted for its ability to grab and transport nitrous compounds.

What does DEF do?

Without getting into the complicated chemistry, DEF is injected into the exhaust system, where it binds to NOx and turns it into less-harmful emissions.  This is why the usage of SCR systems is now becoming mandated across North America.

Is DEF toxic?

Not under normal circumstances, no.  Urea is only harmful in large quantities, so just don’t drink a bottle of the stuff.

Does DEF need to be refilled?

Yes.  As the DEF does its job, it will slowly deplete.  It has to be regularly refilled, in the same way, you refill your gas, oil, and other fluids.

How often does DEF need to be refilled?

There’s no clear answer here; it depends on a number of factors including the energy efficiency of your engine and the size of its DEF storage tank. As a very rough estimate, a typical diesel vehicle will use 2-4 gallons of DEF for every 100 gallons of diesel fuel.  With most DEF tanks being between 15-20 gallons, this works out to something like 5,000-6,000 miles per refill.

How is DEF refilled?

To make it refills easy, most vehicles today place the DEF refill cap near the fuel cap. Occasionally, it may be in the engine compartment.  Either way, there’s nothing special to the filling process.  All you need is a nozzle and perhaps a funnel.

Can an SCR vehicle run without DEF?

Almost certainly not; SCR vehicles will have systems in place to prevent this.  Some will refuse to run at all if the DEF tank is dry, others will force the vehicle into a slow low-power mode to let them limp to a service station.

What’s the easiest way to get DEF?

While service stations are beginning to stock Diesel Exhaust Fluid as standard, this is not entirely commonplace.  For most fleets, the best option is to hire a DEF delivery service to keep on-site tanks stocked up.

Contact Bird Fuels to learn more about DEF delivery services in Ontario.

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