What is AdBlue? diesel exhaust fluid explained

What is AdBlue made of?

Ampol describes AdBlue as a solution of urea and distilled water made to the ISO 22241 quality standards. That standard calls the fluid AUS 32, and it is 32.5% urea and 67.5% deionised water. AdBlue is a registered trademark of the German Association of the Automotive Industry (VDA); diesel exhaust fluid, DEF and AUS 32 are other names for the same kind of product.

What does AdBlue do?

It cleans up the exhaust, not the engine. Ampol says that when AdBlue is heated it turns into ammonia and carbon dioxide, and the ammonia reacts with nitrogen oxide gases to produce nitrogen and water vapour. This happens in the exhaust system, after the diesel has burned, so AdBlue does not add power or change how the fuel burns.

Which vehicles need AdBlue?

RAC WA says many trucks and some diesel light vehicles use AdBlue, including many European diesels, and that new Toyota Prados sold in Australia have a diesel exhaust fluid tank. Petrol cars do not use it. Check the owner manual or look for a separate AdBlue filler, which RAC WA says is usually next to the fuel filler; if the vehicle has no AdBlue tank, it does not need it.

How much AdBlue does a car use?

RAC WA says AdBlue tanks typically hold 15 to 20 litres and estimates use at 10 to 15 litres per 10,000 km. The dashboard shows a warning when the level is low. Dosing is typically 2 to 6% of the diesel used, so a vehicle that burns more diesel, such as a loaded truck, uses more AdBlue.

What happens if AdBlue runs out?

Do not let it run out. RAC WA says the vehicle may not start, or limp mode may switch on, which reduces power and turns off some functions. Top up when the warning appears.

What if AdBlue goes in the diesel tank?

Do not drive the vehicle or turn on the ignition. RAC WA says the fuel system must be drained and checked by a technician.

AdBlue price: pump or bottle?

RAC WA said in March 2025 that a 10-litre bottle costs about $60, and that filling from an AdBlue pump at a service station is generally cheaper per litre. Ampol says its AdBlue is sold at the pump at over 150 truck access sites nationally, or in 10-litre packs at selected locations. Prices change, so check the pump or shelf price before you buy. FuelRadar does not report AdBlue prices.

Plan diesel and AdBlue together

If you are planning a long diesel trip, compare reported diesel prices along the way and check which stops sell AdBlue. Where FuelRadar has facility details for a station, AdBlue is listed with its other facilities in the station list; confirm with the station before relying on it.

Sources and limits

What AdBlue is, which vehicles use it, typical use, what happens if it runs out and the March 2025 bottle price are from RAC WA. Its composition, standard and chemistry are from Ampol's AdBlue page and the Wikipedia article on diesel exhaust fluid. Your owner manual is the source for your vehicle. Sources checked 27 October 2026.