AdBlue is the trade name of DEF (Diesel Exhaust Fluid) – a solution composed of water and urea (a substance found in urine, which is also used for cosmetics, glue and fertilisers). Water in AdBlue is demineralised, therefore much cleaner than tap water.

Although a single truck emits small amounts of nitrogen oxide, thousands of engines emitting the same amount leads to negative effects in the long term.

AdBlue is the trade name of DEF (Diesel Exhaust Fluid) – a solution composed of water and urea (a substance found in urine, which is also used for cosmetics, glue and fertilisers). Water in AdBlue is demineralised, therefore much cleaner than tap water.

Although a single truck emits small amounts of nitrogen oxide, thousands of engines emitting the same amount leads to negative effects in the long term. European legislation has encouraged manufacturers to find new ways to reduce harmful emissions, therefore AdBlue was introduced, along with current Euro 6 emissions standards which demanded a 67% drop in nitrogen oxide emissions.

It is important to make sure your truck or HGV complies with Euro 6 emission standards to avoid causing air pollution which can lead to irritation to the eyes, nose and throat – the latter causing coughing and breathing difficulties. AdBlue has proven highly effective at helping trucks comply with Euro 6, its introduction saw nitrogen oxide emissions decrease by up to 90%.

How AdBlue works

You’ll most likely find AdBlue is topped up via a blue filler cap. On many diesel engines it is located behind the fuel cap. It is not a fuel additive to be injected into engines, it is added to the catalyst system in an exhaust system.

When a truck runs, tiny quantities are injected and they combine with exhaust emissions, breaking down harmful mono-nitrogen oxides in diesel exhaust. As a result, the nitrogen oxide is turned into nitrogen and water vapour.

Every 350 to 600 miles uses around 1 litre of AdBlue but the exact rate depends on the size of a vehicle’s engine and the owner’s driving style. There may be more information on usage rates in your vehicle handbook or you could consult with a mechanic. Keep in mind your dashboard will indicate when your AdBlue tank needs filling.

Things to consider when buying AdBlue

AdBlue can be sold under different names, examples are Bluedef and BlueTec however, it is the mixture of urea and water you should look out for, they’re not all the same. You should buy AdBlue with 32.5% urea and 67.5% de-ionised water.

Using the incorrect mixture can result in damage to the engine, the SCR catalytic converter and affect steering. If a solution is denoted by the ‘AdBlue’ trademark, then you can rely on it meeting the correct requirements.

It is wise to buy a filler cap that locks to avoid theft or contamination of fuel. Thieves often mistake AdBlue storage tanks for unprotected fuel tanks. Having a locking cap keeps your reserve more secure, reducing the risk of leakages which could bring your engine closer to limp mode. When in limp mode an engine’s performance restricts to limit its emissions.

At Truckspares365, the most popular trucks we sell AdBlue filler caps for are DAF and Scania HGVs. We also provide AdBlue filler caps for Mercedes, Iveco, Man, Renault and Volvo trucks. Our caps come in a range of shapes and sizes; you’re bound to find one that suits your vehicle.