What is AdBlue?

A question I’ve found myself answering quite frequently of late is “what is AdBlue and what does it do?”. This is thanks to more and more manufacturers applying it to their diesel engines in their attempts to keep them as clean and efficient as possible.

So what is AdBlue?

Contrary to popular belief, AdBlue is not made of pig urine and isn’t actually blue. It is, in fact, a clear, non-toxic mixture of high purity, man-made urea and de-ionised water.

Whilst it is an additive used to reduce diesel emissions, it isn’t actually mixed in with the diesel. It has a separate reservoir and is not filled through the diesel filler.

Heavy goods vehicles, buses and vans have used AdBlue technology since as early as 2004. It’s relatively new to most car manufacturers but some, Volkswagen and Mercedes for example, have been using it for nearly as long.

What does AdBlue do?

Diesel combustion engines create harmful emissions such as nitrogen oxide (NOx). You’ll have heard of this if you kept up with the VW emissions scandal.

AdBlue is injected directly into the flow of exhaust gases in minuscule amounts. At high temperatures, it turns into ammonia and carbon dioxide. These gases react with the nitrogen oxide and turn it into harmless hydrogen and water.

This reduces the harmful emissions being produced by your car and turn reduces its negative impact on the environment. In the current climate, it does an important job.

Does my car use Adblue?

If your car has a petrol engine, the simple answer is no. It’s only used on vehicles with diesel engines but even then, not all diesel cars use it. There are plenty of ways to find out if yours does use AdBlue.

You’ll be able to find out from the owner’s handbook. You can check for an AdBlue filler cap – it’ll be a blue cap and you’ll either find it in the boot, next to the fuel filler or under the bonnet. Some models even have clues in the name. Look for terms such as ‘blue’ or ‘SCR’ – Volkswagen use ‘BlueMotion’ for example.

If you’re still unsure after checking all of these, you can always contact your local dealer and they’ll be able to let you know. Realistically, though, it’s something you should have been told about when you bought the car.

How and when do I use AdBlue?

It’s simple really – you top it up when it gets low just like you would with your oil or screenwash. As I mentioned before, there will be a separate filler cap into which you pour the AdBlue. You may need a funnel depending on where the filler is situated.

On some cars, you can see a specific AdBlue range, just like you can see your fuel range. On others, you won’t know until there’s around 1500 miles worth left in the tank. That’s when you’ll start getting warnings and it’ll count down from there,

Whilst it is non-toxic, it’s still important that you wash your hands after use and clean up any spillage. It can cause irritation to your skin and eyes and if left on your car’s paint, it can crystallise and damage the paint.

How long will it last and what happens if it runs out?

AdBlue range can vary depending on a number of factors. Average consumption is around 1 litre every 600 miles. It can be as high as 1 litre every 350 miles, however, depending on how aggressively you drive.

Tank size varies from car to car. Smaller cars will take around 10 litres whilst larger cars such as SUVs will have tanks as big as 19-20 litres.

It’s very important that you don’t let your car run out of AdBlue. Once it has run out, you will not be able to restart the engine until you’ve topped it up again. It’s probably worth keeping a small bottle in your boot just in case this happens in the middle of nowhere.

Where can I buy AdBlue?

You can buy AdBlue at pretty much any garage, petrol station or car accessory store such as Halfords. Some supermarkets sell it, too.

It comes in containers ranging from 1 litre to 10 litres. Smaller bottles have a specially designed neck that allows you to fill up your AdBlue without any spillage.

It’s not particularly expensive. A 10 litre bottle from Halfords is £12.50 and, if you need, they’ll fill it up for you at a small cost.

So now you know what AdBlue is and what it does for your car. If you have anymore questions, feel free to send them our way in the comments section or via our Facebook and Twitter pages.