Over the past few years, diesel engines have come under the scrutiny of legislators, not least because of the diesel gate scandal, due to high emissions that do not fit in with sustainability policies. As a result, manufacturers have had to take action and develop greener diesel engines. 


Nowadays, the pollution level produced by cars has firmly reduced. The development of the automotive field was a particular help to this change - mainly thanks to the manufacturing of electric and hybrid vehicles. More generally, a more connected approach to how renewable sources are generated represented the answer to many issues, leading to the development of scientifically based solutions that could improve the mechanics of waste reduction. Today's concerns have become more reinforced than ever, mainly since the pressing Euro 6 emissions standards in September 2015, demanding a 67% drop in nitrogen oxides (NOx) in diesel cars' exhaust emissions. 


Carmakers have thought about two ways of meeting the new standards concerning reducing emissions:


  • Selective catalytic reduction (SCR): This measure uses an exhaust fluid, commonly called AdBlue, to break the NOx in exhaust gasses down into harmless elements before it's expelled from the car

  • Exhaust gas recirculation (EGR): using a recirculation system to replace some of the exhaust gas, lowering the oxygen levels in the combustion chamber and consequently reducing the volume of nitrogen converted into NOx. You won't need to use AdBlue if your car is supplied with this system.


‚ÄčIf your car is fitted with an SRC system - or if you are planning to buy a diesel car in 2022, this article is for you - and you probably already heard about AdBlue. But what is AdBlue, exactly?


You will find many amusing stories surrounding the composition of this liquid that helps with cleaning up your car's emissions. You might have heard that it's a fluorescent blue fluid that works towards your vehicle's fuel economy. Or, even better, that the actual composition is a mix of pig's wee and other atypical substances. We are pretty far away from the truth here - although we are talking about a fascinating and powerful product that will help diesel cars clean up their air.


Are you curious to learn more about AdBlue? Keep on reading. In this Karfu guide, we will investigate the use of AdBlue for your diesel, helping you with some instructions and tips for a perfect product's usage.


So What Is AdBlue, then?


AdBlue (also known as DEF, which stands for Diesel Exhaust Fluid) is a liquid injected into a diesel car's exhaust system to clean up the emissions. You are more likely to find this product under the simple name of AdBlue, though, as it's the brand name commonly used to designate this product.


The composition of the compound can sound pretty peculiar at first: it is made of 32.5% urea and 65.7% deionised water. Yes, the first one is the main component of urine - but as we mentioned in our introduction, there's nothing to worry about: the product is entirely created in a lab, wholly developed for the chemical and automotive industries. Hence, as multiple urban legends allegedly suggest, it's not related to human sourcing. Ah, it's also a legend that you will discover the same benefits if you substitute AdBlue with actual urine. So if you don't want to risk an epic and uproarious fail, don't try this at home. 


AdBlue is consumed in a selective catalytic reduction (SCR) - as we mentioned, an advanced active emission control technology that converts nitrogen oxides, also referred to as 'NOx' - with a catalyst into diatomic nitrogen and water. A reductant - typically anhydrous ammonia, aqueous ammonia, or a urea solution, is added to a stream of flue or exhaust gas and is reached onto a catalyst, reducing the tailpipe emissions that lowers the concentration of nitrogen oxides- in the diesel exhaust emissions from the newest and most recently manufacture diesel engines. It is, in fact, the most effective in reducing nitrogen oxide emissions and, therefore, by far the most widely used in the latest generation of cars.


A true non-toxic or inflammable product, it is made with the finest urea and purest water, and it is a synthetic, colourless, and odourless substance. AdBlue does not have hazardous properties, and it's not harmful to the environment.


What do you need AdBlue for?


You will need AdBlue if you own a diesel car with an SCR system, as it's capable of cutting down nitrogen oxides from exhaust gasses by 90%. 


These are good numbers and is what makes AdBlue such a valuable ally to reduce the emissions propagated by diesel vehicles - and help green-minded motorists who try to make an environmentally-friendly choice. 


The more significant portion of diesel cars registered after September 2015 will need Adblue to reduce their pollution. You will start buying this product if you own a Euro 6-compliant diesel Audi, BMW, Citroën, Jaguar, Land Rover, Merced-Benz or Peugeot - they are all very likely to use AdBlue technology. The car's model name will help you as well, as they usually have the word 'Blue' or 'SCR' in them. 


Where can you buy AdBlue, and how much does it cost?


Because AdBlue is compulsory for diesel cars, you will find it anywhere you'd buy other products for your vehicle - including at petrol stations and stores like Halfords - and car dealers, hardware shops, garages, and the web at competitive prices. 


Usually, you can expect to pay around 20 pounds for 10 litres.


Where can I find an AdBlue pump?


It will be hard if you own a diesel car to find an AdBlue pump that fits your vehicle in motorway service stations. They are usually reserved for HGVs and coaches - their nozzles are traditionally more diminutive size, so it will hardly fit your car's tank. However, if you can locate one, a pump is usually a better way to refill your tank, as the refilling process is tidier than using bottles - and it's also cheaper. Look around at the petrol station if you see one pump that fits your vehicle.


How often will I need an AdBlue top-up?

The quantity of AdBlue usually needed depends on the type of driving and the number of miles covered. 


How do I top up my car with AdBlue?

Most AdBlue tank filler spouts are located next to the diesel filler, and they usually have a blue cap. You can spot a place for a filler near the boot and spare wheel well. Can't you find it? Have a look at the car's handbook - you will easily find the location.


What happens if my car runs out of AdBlue?

Most cars will display the warning light when AdBlue starts to run low; this usually illuminates when there are around three litres of fluid left, giving you approximately 1200 miles to refill it. 

Don't ignore the warning signals: if you keep driving until the AdBlue entirely runs out, the car's emissions and performance will be widely affected. Once you turn the engine off, the car won't start if you try until you refill it with AdBlue - so always better to be prepared.


Putting diesel in the AdBlue tank - is it dangerous?

If you accidentally poured diesel into your car's AdBlue tank, it's better not to start the engine and call your call dealer or breakdown service to get it drained. It's always better not to turn your car on, as it may cause unexpected damages, particularly putting both the catalytic reduction and the injection system at risk - always better to have an expert hand who can deal with the drainage and avoid any possible damage related expense. 


Putting AdBlue in the diesel tank: is it dangerous?


Same as above, with the difference that, in this case, you would put at risk the engine and fuel system. Always look for a professional in this case to avoid any possible complications.




Does it matter what AdBlue you use?

You can use different types of AdBlue. AdBlue is just a commercial name of one of the other brands on the market- so buying from a different brand or with a different name won't change the results. One important thing to remember is to buy the right AdBlue for cars with different labelling (usually ISO 22241). This will ensure your vehicle won't damage the catalytic converter in its exhaust - whose replacement would represent a pretty consistent expense.


How efficient is AdBlue?

AdBlue is a potent liquid that is popular to be highly efficient. A study conducted by Leeds University in 2017 found that a Volkswagen Polo with a 1.4-litre diesel engine and no AdBlue system produced more NOx gasses than a 13-litre diesel lorry with the system fitted. 


Does AdBlue increase my car's performance?

Unfortunately, AdBlue won't turn your vehicle into a supercar. Totally the opposite: running out of AdBlue could lead to unpleasant flip-side effects – some cars will revert to a limited-performance limp mode if they run out of AdBlue.

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Silvia Iacovcich 14/07/22