What AdBlue Does and Why You Need it
Not many car owners in America need to know about AdBlue, since it is only relevant to a niche market: diesel-engined cars and trucks, which are not overly popular in the United States. Essentially, AdBlue is an additive that can reduce nitrogen oxide (NOx) emissions, reducing pollution and helping drivers meet increasingly stringent emission regulations. It does this by combining with exhaust emissions, breaking down the NOx into nitrogen and water, which are both non-toxic. In the US, this product is referred to as diesel exhaust fluid (DEF).
So, what is AdBlue/DEF actually made of, and how does it work? The chemical composition is 32.5% urea - CO(NH2)2 - and 67.5% deionized water. It is used in vehicles with selective catalytic reduction (SCR) technology that have a separate tank to house the fluid. It gets heated in the exhaust and the urea breaks down into ammonia (NH3) and carbon dioxide (CO2). But instead of creating two different harmful greenhouse gases, the nitrogen ions from the ammonia combine with those of the NOx, while the hydrogen ions combine with the oxygen.
Not All Cars Require DEF
Nitrogen oxide is not your average car emission - only diesel engines like those found in the VW Passat TDI have this problem, and only more modern variants are able to make use of this handy substance. They have a special tank and pump for it, as well as an AdBlue warning light to let you know when it is running empty and needs to be topped up. Just a few of the cars which use AdBlue in the USA include the diesel models of the :
- Chevrolet Colorado/Silverado
- Chevrolet Suburban/Tahoe
- Ford F-Series pickup trucks
- Jeep Wrangler
- Mercedes-Benz Sprinter
- GMC Savana
- Ram pickup trucks
Most fleet managers prefer diesel-powered vans for their better fuel economy, so DEF is essential in newer models. The same is true for Class 8 semi trucks, which are still used to move cargo around the US.
How to add AdBlue/DEF and how often
Modern cars equipped with an SCR system have a warning light that notifies you when the DEF needs topping up. How long AdBlue or DEF lasts varies between different models and driving habits, so there is no standard schedule as with other car maintenance. How to add AdBlue is pretty simple thanks to manufacturers being mindful of the new emission regulations. There is usually a filler spout beside the fuel cap on most trucks.