Diesel exhaust fluid (DEF) is an essential component of the Selective Catalytic Reduction (SCR) process. Heavy-duty engine manufacturers use this to comply with EPA regulations. Diesel exhaust fluid is a mixture of high-purity synthetic urea and deionized water that is used in diesel vehicles’ Selective Catalytic Reduction (SCR) systems. DEF is used to aid in the conversion of NOx to harmless nitrogen and water. 

Is It Necessary for Diesel Engines? 

DEF is an absolute must have with Diesel Engines. The EPA has mandated that all diesel engine manufacturers install a warning system that alerts the driver when the DEF tank is almost empty. 

The truck will stop functioning if you ignore the DEF warning. A truck may have a finite number of engine starts by entering a reduced power mode that some diesel engine manufacturers enable. However, eventually the diesel engine won’t start. 

How Much Do You Need? 

The amount needed will vary depending on the diesel’s usage and miles per gallon. As a general rule of thumb, a light-duty truck will use 2 to 3 gallons of DEF every 800 miles. Most new trucks, however, will travel between 8,000 and 10,000 miles on a tank full (10 gallons). 

Where To Buy DEF? 

It’s critical to realize that an empty DEF tank will cause the engine to shut off if you don’t fill it. Since DEF is not widely available, you don’t want to be stranded somewhere with an empty tank. DEF is frequently purchased at Walmart, Target, O’Reilly’s, NAPA, SAPP Brothers, and for online shoppers, Amazon. 

What Could Be a Negative Aspect of DEF? 

Diesel particulate filters (DPF) and selective catalytic reduction (SCR) may require maintenance or repairs because of clogging. Due to the complexity of these systems, even a simple clogged filter can result in pressure and temperature differentials that can impair an engine’s performance.