16/07/2019 News

The ultimate guide to Adblue



If you own a diesel, chances are you need to use AdBlue – a diesel exhaust fluid (DEF) is used in millions of cars, light commercial vehicles, HGVs, buses and coaches across the world. But what is it, what does it do, how does it work and how do you use it to ensure your car performs efficiently and safely? Read on to learn more.


What is AdBlue?

AdBlue is a DEF mixture used in all heavy-duty diesel engines produced after January 1st, 2010 and most passenger diesel engines made after September 2015 – particularly Euro 6-compliant models. AdBlue isn’t a fuel additive as it’s added to the exhaust gas after combustion has taken place. AdBlue is a worldwide trademark of the German Association of the Automotive Industry (VDA).

AdBlue engines use selective catalytic reduction (SCR) technology to reduce nitrogen oxide (NOx) exhaust emissions and can usually be identified through the ‘SCR’ or ‘Blue’ in the vehicle’s model name.


What is AdBlue made of?

AdBlue is a colourless mixture of high-purity urea (32.5%) and deionised water (67.5%), as noted in the ISA 22242 standard. As the urea is heated in the SCR catalytic converter, it turns into ammonia, which reacts with the NOx, breaking it down into safe water and gases.


Is AdBlue toxic or dangerous?

AdBlue DEF is water soluble, biodegradable and non-hazardous, however you should rinse thoroughly in case of contact, avoid AdBlue vapours, and clean surfaces that come into contact, as it is slightly corrosive to certain materials.

Does AdBlue freeze? 

AdBlue can freeze at temperatures below -11°C, however it will usually thaw due to the heat of the engine in cold winter conditions, without any change in concentration or effectiveness.

If driving in exceptionally cold conditions, it can be a good idea to keep a bottle of liquid AdBlue in your vehicle to top up the tank in case of freezing – automatic warming systems can take up to 20 minutes to thaw frozen AdBlue tanks.


What does AdBlue do and how does it work?

As diesel engines are running, AdBlue is sprayed into the exhaust gas via a dosing control system, reacting with the NOx and turning it into water, carbon dioxide (CO₂ and nitrogen gas) nitrogen gas – through this method, AdBlue reduces total fuel consumption by 2-6%. AdBlue is kept in a separate tank to the fuel, however.


Are there alternatives to AdBlue?

You should not use water instead of AdBlue. The VDA notes that vehicles should not use urea solutions not denoted by the ‘AdBlue’ trademark. While inexpensive, these can be dangerous, damage the engine, affect steering and harm the SCR catalytic converter, so it’s always best to stick with legitimate AdBlue.

Why do vehicles require AdBlue? 

Nitrogen oxide is a harmful gas that can damage the respiratory system, reducing lung function, increasing allergen exposure and the risk of respiratory illnesses. It also helps form fine particulate pollution and ground ozone – both harmful – and can also harm vegetation.

It’s for these reasons the European Union sets limits on vehicles’ NOx emissions, in order to improve air quality and reduce the threat of deaths and illness from diesel pollution.


What should I do if I run out of AdBlue?

It’s impossible to drive without AdBlue – your engine will not start, and you’ll see a notification noting ‘AdBlue is empty’. This notification will also appear when your AdBlue tank is running low.

Most diesel vehicles require an AdBlue top-up every 3,000-4,000 miles, depending on the engine. Check your vehicle manual for a figure specific to your make and model.


How to refill AdBlue

HGV operators can use AdBlue or DEF pumps at petrol stations to refill. These pumps should never be used by car owners, however, as the pump flow rates are far too high for small passenger vehicle AdBlue tanks and will overfill them extremely quickly.

AdBlue can be refilled at a mechanic, workshop or dealership, and manufacturer-specific refill kits and canisters are also available. However, different makes and models place AdBlue tanks and fillers in different locations, so always follow the instructions.

Once you have topped up your AdBlue, don’t turn on the ignition until your vehicle computer has confirmed the refill. This can take a couple of minutes.


Total’s AdBlue products 

Total offer AdBlue in bulk, barrel and small commercial vehicle packs, and offer all the benefits of fully compliant AdBlue to drivers and fleet operators.

As well as reducing NOx without harming engines, Total AdBlue also features Total Diaxol, an additive within the solution that cleans SCR systems, improving their cold and stop-start performance. Reducing clogging in exhaust, Diaxol has been shown to remove the risk of clogging for up to 50,000km and reduce maintenance costs.

Learn more about how Total AdBlue and Diaxol can improve your fleet emissions and lower maintenance costs today.