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What is AdBlue?

If you’ve bought a brand new, diesel-powered car in the past couple of years, then, sooner or later, you are going to need to get your hands on some AdBlue. However, what is AdBlue? Why do you need it? And where can you buy some?

Read on for carwow’s quintessential guide to AdBlue… 

AdBlue and diesel emissions:

To limit climate change, both car manufacturers and the European Union have been introducing more and more emissions regulations and alternative fuels in recent years. This has meant more electric cars on the road; big, gas-guzzling engines being replaced by smaller units with turbochargers; and, in 2015, the introduction of Euro 6 legislation.

Euro 6 came into force in the EU to strictly regulate the harmful waste products made by large and powerful diesel engines, especially nitrous oxide. To follow the new rules, car manufacturers fitted their diesel-powered cars with AdBlue treatment. This liquid turns nitrous oxide into a mix of more harmless byproducts. 

In 2017, Leeds University research found that a 1.4-litre, diesel-powered Volkswagen Polo without AdBlue produces as much harmful nitrogen dioxide as a lorry powered by a 13-litre diesel engine with AdBlue. As a result, the benefits of AdBlue couldn’t be clearer.

What does AdBlue do?

Without AdBlue, diesel cars from as small as a Volkswagen Golf to as large as a Mercedes G-Class would produce too much nitrous oxide to be allowed on the road under Euro 6 rules. AdBlue is a non-toxic liquid – made mostly of water and urea (yes, the stuff in pee) – that is used as a part of selective catalytic reduction (SCR). SCR breaks down the nitrous oxide produced by diesel engines: by squirting small splashes of AdBlue into the exhaust, it turns the waste into harmless water and nitrogen. Hey, presto! – your car is suddenly a whole lot kinder to the environment.

Do I need AdBlue?

If your car requires AdBlue – i.e., it’s a diesel that conforms to Euro 6 legislation – and you let it run out, the engine won’t start. Luckily, almost all cars that need AdBlue have a display or a warning light that will let you know how much is left and when you need to give it a top-up.

An AdBlue gauge in a Ford Transit van

When do I refill AdBlue?

How long your AdBlue lasts depends on a lot of factors, such as the size of a car’s AdBlue tank, your own personal driving style and your car’s fuel consumption. However, to give a rough estimate, the AA reckons you should burn through around a litre of AdBlue for every 600 miles you drive.

When you’re refilling your AdBlue, you can’t ‘splash and dash’ the way you can with fuel. If you refill only a small amount, it won’t register when you check the measuring gauge inside your car. Also, if you buy a bottle of AdBlue so that you can refill your car’s levels yourself, you have to use all of it; a half-empty bottle won’t keep for later.

How do I refill AdBlue?

Refilling AdBlue is like refilling your petrol tank. In the vast majority of cases, you’ll find the pipe for your car’s AdBlue beneath the fuel filler cap, next to your diesel filler. Just pour the AdBlue in (or don’t, if you’re getting a mechanic or manufacturer to do it for you) and you’re all set!

The AdBlue pipe on a Volkswagen Passat Estate

Where to buy AdBlue (AdBlue pumps):

Bottles of AdBlue can be found in most petrol stations – especially those belonging to chains like Shell or Texaco – and motoring shops, such as Halfords.

It’s also possible to refill your AdBlue from a pump at petrol stations, similar to fuel. However, stations with AdBlue pumps are rare in the UK.

If your car is being serviced and your AdBlue levels are running low, the garage can top up your levels for you. The same can be true if you buy AdBlue directly from your car’s manufacturer, with the bonus that some of them free limitless top-ups.

When you buy your AdBlue, check for a code on its label beginning with ‘ISO-22241’. This means that the AdBlue in question won’t damage your car’s SCR system, which can prove very expensive to repair or replace. Picking the wrong AdBlue can also void your car’s warranty.

AdBlue prices:

The cost of AdBlue can vary. However, in most cases, you can find a five-litre bottle on store or petrol station shelves for around £5.

Topping up AdBlue at the pumps or during a service can prove much more expensive, so you’d best stick to refilling your car yourself whenever you can.

The AdBlue pipe on a Mercedes E-Class Estate

Popular manufacturers with AdBlue:

Audi AdBlue:

Your Audi will let you know when it is 1,500 miles away from running out of AdBlue by flashing a warning message on its digital screen. An Audi main dealer service centre can refill your AdBlue levels at a fixed rate of £1.50 per litre.

BMW AdBlue:

BMW claims that its cars can last an average of 15,000km (9,321 miles) before needing to be refilled with AdBlue. If your range drops below 1,600km (994 miles), a warning will automatically come up on your display, counting down the miles until your car’s AdBlue tank needs refilling.

Mercedes AdBlue:

If you buy a bottle of AdBlue from an official Mercedes service centre, they will refill the tank for you for no extra charge. A warning message will flash up on the car’s dashboard when you’re hitting your reserve of AdBlue.

Volkswagen AdBlue:

Volkswagen gives you a 1,500-mile warning that your AdBlue’s running low with a countdown until the tank’s empty.

The company is also one of the few to quote what you can expect from a tank of AdBlue across its model range. So, a Volkswagen Passat with a 13-litre AdBlue tank should be good for up to 6,500 miles between top-ups. The biggest car the brand sells, the Volkswagen Touareg SUV, has a 19.5-litre Adblue tank, which will last up to 7,000 miles between top-ups.

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