Guides | What Is AdBlue?

What Is AdBlue and How Does It Work?

AdBlue is a diesel exhaust fluid that more and more drivers are buying as Euro 6 diesel engines often require it. To meet environmental standards and keep your engine running, you need AdBlue. But what is AdBlue used for and what’s the best way to buy it? Well, we’re here to help you out by breaking down everything to do with this handy product.

What is AdBlue fluid made of?

AdBlue is made up of 67.5% deionised water and 32.5% urea. It’s a clear non-flammable liquid helpful for diesel vehicles. It’s a high-quality human-made solution.

Some believe it’s made from pig urine due to urban legend and misinformation. The type of urea used in AdBlue is made in a laboratory.

Let’s explain what this super helpful product is actually made from:

  • Urea: a chemical compound that can be found in small quantities in animal and human urine, but the chemical compound is also found in fertilizer and in manufacturing as a starting material.
  • Deionised water: water that has had all mineral particles removed from it. It’s also known as DI water or Type II water. Removing all the minerals means it doesn’t react with the urea.
Mechanic opening a car to check Adblue levels of a car in a vehicle repair shop

What is AdBlue for?

It’s a necessary diesel exhaust fluid that acts with your vehicle’s Selective Catalytic Reduction (SCR) system to reduce the number of harmful gases released from the exhaust.

What is AdBlue used for in diesel engines?

Well, the core use around the world is to improve the environmental impact of diesel engines. Once you refill your AdBlue tank, it flows into the SCR and begins to break down any nitrogen oxide (NOx) released from the exhaust pipe.

Any NOx is broken down into nitrogen and oxygen, which then leaves the exhaust pipe as a harmless steam instead of a toxic gas.

NOx has been linked to asthma and other respiratory conditions, so reducing it is an excellent way to limit the impact of diesel engines on the environment and the health of drivers.

What is AdBlue for cars?

Any car with a diesel engine has an AdBlue tank. It works as a diesel exhaust fluid (DEF) and not as a fluid additive. You can usually find your tank refill filler cap beside your fuel tank, under the bonnet or sometimes in the boot of your car.

Diesel cars require AdBlue. Those that meet the new Euro standard (most made after 2015) require it to reduce emissions. If your car has an SCR and no AdBlue in the tank, it won’t start without it.

What happens if I disable my AdBlue?

While it’s technically possible to disable the AdBlue system and remove the dashboard warning lights in your vehicle, it’s illegal to remove your AdBlue system and can result in prosecution.

The good news? Buying the stuff is affordable and one you need to pay if you want to stay on the road.

If you’re a business owner, sole trader or fleet manager thinking about buying AdBlue, you can buy it using a fuel card. Just make sure your fuel card is one that lets you buy the product.

How much AdBlue do I need?

How much AdBlue you should use varies depending on your vehicle, tank size and driving style. You can find out how much your vehicle needs from your vehicle dealer, manufacturer or mechanic.

Some vehicles require an AdBlue refill every 600 miles, while some can last 12,000 miles.

You’ll know when you need to refill your tank when the display screen flashes a warning, like how your vehicle tells you when your fuel tank is low.

How do I use AdBlue?

Most mechanics will refill your AdBlue tank during your vehicle service or maintenance appointment. But refilling it yourself can be faster, cheaper and easier.

To use AdBlue yourself, there are some dos and don’ts to keep in mind. Improper use of the product can cause problems for your vehicle including contamination of the SCR system so it won’t function as it should. Here’s everything you need to know:

5 simple things to do when using AdBlue

1. Pour it into the AdBlue tank of your vehicle — the filler is clearly marked

2. Make sure the container and tank seals are intact

3. Keep your equipment free of dirt and dust

4. Clean your equipment with demineralised water

5. Store your AdBlue at an ambient temperature — above -11˚C and below 30˚C

5 ways to not use AdBlue

1. Don’t put AdBlue in your diesel tank

2. Avoid putting diesel in your AdBlue tank

3. Don’t mix it with any other liquids

4. Never leave spilled AdBlue on the floor

5. Don’t override your AdBlue system — it’s illegal and could damage your vehicle

If you do accidentally put AdBlue in your diesel tank or diesel in the AdBlue tank, call your mechanic or a breakdown service and have the tank drained before you start your vehicle. Starting your vehicle while the wrong fluid is in the incorrect tank can lead to severe engine damage.

How much does AdBlue cost?

The price varies depending on where it is purchased from, current inflation, VAT and how much you buy. A 5-litre drum can cost around €22 to €25 at the time of writing. Suppliers of AdBlue estimate drivers in Ireland use 60 to 70 million litres every year in total.


Where can I buy AdBlue?

It’s the leading brand of exhaust fluid, so it’s available at most supermarkets, specialist vehicle shops and service stations on the motorway across Ireland. You can buy the product with cash, credit cards, debit cards and fuel cards.

Why buy AdBlue with a fuel card?

Most drivers buy AdBlue with cash or their debit or credit card. But sole traders and businesses can significantly benefit from using their fuel cards. Here’s why purchasing it with fuel cards is better than any other option:

  • Account management: check your fuel card spending any time on your phone, tablet or computer
  • Transaction history: any purchase is included in your regular invoice
  • Secure payments: no need to give drivers cash or ask for receipts later
  • Accurate accounts: download invoices and submit them for business expense claims

Best fuel cards to buy AdBlue

Fuel cards are an alternative way of paying for fuel. Some of the best cards in Ireland can be used to buy AdBlue too. The best fuel cards to buy AdBlue with are the DCI Pump Saver, Texaco Fastfuel and the DCI One REV. Here’s where each of these cards can be used and what for.

Fuel Card  Where to use it What to buy with it
DCI Pump Saver fuel card to buy AdBlue, petrol and diesel

DCI Pump Saver

Stations: Circle K, Top Oil, Texaco, Emo, Maxol, Campus, Amber Oil



All premium fuels

Car washes


Fuel card from DCI to buy AdBlue, petrol and charge EVs in Ireland


Stations: Maxol, Texaco, Amber, Circle K, Star, Emo, Top, Circle K

Charge points: ESB, NewMotion, IONITY and Fastned



EV and hybrid charging costs

All premium fuels

Car washes


Fuel card for Ireland from Texaco

Texaco Fastfuel

Stations: Texaco, Maxol, Great Gas, Emo Petrol


All premium fuels

Car washes



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