A key concern for any diesel owner is the diesel exhaust fluid shelf life and whether or not it will go bad.
Diesel exhaust fluid (DEF) is added to the exhaust cycle of the diesel engine to cut down pollutants. Running out or getting bad fluid can cause diesel engine problems — including not being able to drive the truck.
Diesel exhaust fluid shelf life?
When buying DEF, it is important to pay attention to where you are getting it. First, make sure the DEF fluid is an air conditioned store or in a temperature-controlled building. The heat will cause the chemicals to dissipate, and the fluid won’t work as intended.
Temperature is really the key and more important than the shelf life on the box. For example, Stellantis states in technical service bulletin 25-006-13:
Temperature Estimated Useful Life
32°F (0°C) Indefinite
50°F (10°C) 75 Years
68°F (20°C) 11 Years
86°F (30°C) 23 Months
95°F (35°C) 10 Months
104°F (40°C) 4 Months
122°F (50°C) 1 Month
140°F (60°C) 1 Week
Diesel exhaust fluid shelf life, then, doesn’t really matter — as long as it has been stored properly.
What happens when you put bad DEF in the truck?
Let’s say you screw up and put bad DEF in the truck. Not a big deal right? Just use it up? Well, not exactly.
Adding bad DEF to your truck can cause a variety of problems, according to Ricochetfuel.com. That includes:
- Potential equipment malfunctions and issues, such as unexpected engine shutdowns
- Damage to vital vehicle and equipment components such as the diesel particulate filter and the DEF dosing pump.
- Malfunction or damage to a vehicle’s Selective Catalytic Reduction (SCR) system.
You could also experience less performance from the truck including worse fuel consumption.
The bottom line
Bad DEF is a big deal and you should take precautions. If you do it once, then the best thing to do is drain the tank and start over. If it happens more than once, it would be smart to have a mechanic look over the engine.
