If you operate a diesel car manufactured after September 2015, then chances are, you’ll need to refill the AdBlue tank routinely depending on how many miles you travel. Our guide explains all there is to know about the diesel exhaust fluid, including what it is, where it goes and more.

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What is AdBlue?

AdBlue is a liquid diesel exhaust fluid (DEF) (also known as AUS 32) and is a trade name registered by the German car manufacturer’s association. DEF is required by law to reduce the amount of nitrogen oxide (NOx) emissions produced from diesel engines. All heavy-duty vehicles and diesel cars with engines manufactured after September 2015 that are compliant with Euro 6 standards are required by law to use the diesel exhaust fluid.

Our AdBlue is VDA-licenced and is sourced from the Tennants Group, giving you peace of mind that it complies with AUS 32 and ISO 22241 standards. Call 0330 123 3773 to find out more.

Are AdBlue and DEF the same?

Yes. DEF (diesel exhaust fluid) is just another name for AdBlue.

Why is AdBlue used?

The transport sector is the biggest contributor of greenhouse gases, so is under growing pressure to reduce pollution levels. As a result, diesel vehicle owners are increasingly being affected by new environmental legislation to help reduce the impact of fossil fuels on the planet.

To comply with Euro 6 regulations, many diesel-powered cars built after 2006 require AdBlue to reduce diesel emissions with selective catalytic reduction (SCR). This is used alongside AdBlue to reduce the concentration of nitrogen oxides (NOx) in the diesel exhaust emissions produced from a diesel engine.

Nitrogen oxide (NOx) is a gas that is toxic to human health and can damage the human respiratory system, hindering lung function, and increasing allergen exposure and the risk of respiratory illnesses. NOx also encourages the production of fine particulate pollution and ground ozone which are detrimental to health and vegetation.

SCR technology has been used in buses and heavy lorries for a considerable time already, so its effectiveness has been proven in helping to reduce these emissions.

What is AdBlue made of?

AdBlue is an aqueous urea solution made of 32.5% high purity urea and 67.5% deionised water, as set out in the ISO 22242 standard, hence its official name: Aqueous Urea Solution (AUS32).

Is all AdBlue the same? 

While there are several names for AdBlue, such as Bluedef and BlueTec, the diesel exhaust fluid must contain 32.5% urea and 67.5% deionised water. To ensure it’s of industry standard, it must feature the German Association of the Automotive Industry’s AdBlue logo. While cheaper, solutions without this trademark can be dangerous and damaging to the engine and SCR catalytic converter, so it’s always best to stick with branded AdBlue.

Problems of purchasing cheap AdBlue include:

  • Higher pollution levels
  • Pressure build-up
  • Decreased fuel economy

How does AdBlue work?

AdBlue works alongside selective catalytic reduction (SCR) systems to reduce NOx exhaust emissions. After exhaust gases pass through the diesel particulate filter, AdBlue is sprayed and interspersed into the exhaust stream through a dosing control system as it enters the SCR catalytic converter. The ammonia then reacts with NOx in the exhaust stream and neutralises it to form harmless nitrogen (N2) and water vapour (H2o) while reducing total fuel consumption by 2-6%.

When is AdBlue injected?

AdBlue is not a fuel additive as it’s injected into the exhaust gas after combustion has taken place.

AdBlue is stored in a separate tank to diesel and is injected into the exhaust pipeline before emissions are released. Within the SCR catalyst, NOx emissions are reduced by converting the ammonia into water and nitrogen which are less polluting. These are then released into the atmosphere through the exhaust.

Does my car need AdBlue?

If you own a diesel car then it’s likely it will use AdBlue. You can check your vehicle’s handbook or look for the filler cap that’s located either next to the fuel filler, under the bonnet or in the boot.

How to fill AdBlue

AdBlue comes in secure packaging with clear advice on how to top up your tank. AdBlue is stored in a separate tank so it never actually comes into contact with diesel.

  • Always firmly close the AdBlue tank cover after topping up
  • Use water to clean any spilt AdBlue off surfaces, in your vehicle and off the ground
  • Only use equipment that’s designed for AdBlue to fill your tank
  • Filling your AdBlue tank with anything other than DEF can be expensive to repair
When should AdBlue be refilled?

Your car won’t start without AdBlue. When it’s running low, a notification will pop up on the vehicle’s dashboard to alert you before the tank runs dry.

How long will AdBlue last?

The rate at which AdBlue depletes is around 1 litre for every 350 to 600 miles. The exact rate, however, depends on the engine size, your driving style and the size of the AdBlue tank which usually varies between 5 and 20 litres.

A Volkswagen Tiguan SUV car has a 12-litre AdBlue tank and Passat family a 13-litre tank. On the contrary, Peugeot estimates that its cars can travel 12,000 miles between refilling, the same as its servicing intervals.

Most vehicles require a top-up every 3,000 to 4,000 miles, depending on the engine.

What is the shelf life of AdBlue?

If stored at ambient temperatures of around 24oC, AdBlue will last for around two years. If it’s subject to temperature fluctuations, it’s lifespan will be around 1 year.

Will AdBlue freeze?

DEF freezes at -11oC (12oF) but it will usually thaw due to the heat of the engine in cold weather without affecting its concentration or effectiveness. For AdBlue to work in low temperatures, a sufficient amount of the frozen solution must be melted as soon as possible. 2010 EPA emission requirements necessitate full DEF coolant flow within 70 minutes.

If you’re driving in severely cold temperatures, it might be beneficial to keep a spare bottle of AdBlue with you so you can top up the tank in the event of freezing. Automatic warming systems can take up to 20 minutes to thaw frozen AdBlue tanks.

Can I add antifreeze to AdBlue to prevent it from freezing?

We would advise against it. AdBlue is a specific formulate of urea and water but it also has other compounds of precise quantities to stabilise it. Adding antifreeze would change the exact chemical makeup and decrease the NOx reducing properties and potentially damage the SCR system.

Will AdBlue damage paintwork?

AdBlue is clear, non-toxic and safe to handle. However, as urea has a slightly corrosive impact on metals such as aluminium, AdBlue must be stored and transported in containers made of stainless steel. Diesel vehicles’ SCR systems and DEF dispensers are designed to ensure there is no impact of urea on them.

How should AdBlue be stored?

AdBlue should be stored in a cool, dry and well-ventilated place that is out of direct sunlight.

Bulk quantities are often handled in IBC for storage and shipping.

Are AdBlue emulators illegal?

Yes, AdBlue emulators essentially trick a diesel vehicle engine into running without a SCR system. They disable the pollution control systems and deactivate the warning light on the dashboard that alerts you that the system isn’t working.

Even though AdBlue is relatively cheap, it’s an added cost for fleet operators. Disabling AdBlue use saves business around 5% but increases emissions by up to 2.5 times the safe level.

Latest AdBlue prices

The cost of AdBlue is relatively low and won’t be a huge addition to your business expenses. However, you can keep the price of AdBlue low by purchasing in bulk quantities. The consumption of AdBlue varies according to your vehicles, although it’s around 3% of diesel consumption for lighter vehicles.


Cost of AdBlue storage

AdBlue prices in packs – As with all fuels and oils, the smaller the volume, the higher the price. While AdBlue packs are perfect for small distance vehicles, if you run a large fleet, these packs are less cost effective. However, if you do only require AdBlue in packs, you won’t need to invest in an onsite storage facility, which is of course one less cost to consider.

AdBlue prices in barrel – Purchasing 205-litre barrels of AdBlue will cost less per litre than 10-litre AdBlue packs. To use a barrel, you must also consider the cost of a pump to dispense the DEF solution, which is generally cheap to buy.

AdBlue prices in IBC and bulk – An IBC (intermediate bulk container) can hold 1000 litres of AdBlue and costs less per litre than smaller packs and barrels. If your fleet consumes a large amount of AdBlue, you’ll benefit from larger savings as your desired quantity increases.

Why do AdBlue prices change?

AdBlue prices vary as per the cost of the raw products that make up the diesel solution. There are currently no active urea processing plants in the UK which means that the demand can be an active contributing factor to AdBlue price.

Buying AdBlue in bulk when prices are low helps avoid any price fluctuations and ensures you benefit from the best cost price.

Who sells AdBlue?

When purchasing AdBlue, you must always check to ensure it meets the required specification. Look out for the ISO 22241 number on the packaging, which may also appear as:

  • ISO-22241-1
  • ISO-22241-2
  • ISO-22241-3

This will ensure the AdBlue doesn’t damage your car’s SCR catalyst which can be expensive to repair if a low-quality DEF is used. As long as the AdBlue meets these required specifications, one brand of AdBlue is fundamentally the same.

At Speedy Fuels, we’re a UK-wide AdBlue supplier that can deliver DEF within 48 hours of order in a wide range of quantities. Call 0330 123 3773 to find out more or to place an order.