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AdBlue or Urea: how does it work and what is it for?

Advantages and disadvantages of AdBlue: here’s how it works, how much it costs and what the urea solution is used for in modern cars with the SCR system

10 February 2023 – 11:00

Many motorists have discovered what is adblue only after buying the car. In the following paragraphs, we answer the most frequently asked questions: what is AdBlue used for?, How much does AdBlue cost?, how to put adblue in the car and other curiosities. Let’s dispel the bar sul myths top up AdBlue with helpful shopping tips. AdBlue can also be purchased online, we will explain how to read the labels of the different brands of AdBlue for sale on eBay in the category of fuel additives.

Update February 10, 2023: AdBlue tariffs and new useful content for readers


With the limits of Euro 6 emissions (NOx Nitrogen Oxides of 80 mg/km) car manufacturers realized that the EGR valve alone would not be enough. In some cases it was decided to multiply the EGR valves on the exhaust line. For many other cars it was not possible to do without it use the SCR system from Euro 6C. The need to add AdBlue to a dedicated tank of the car in the same way as for fuel is linked to the presence of the SCR system (Selective Catalytic Reduction – selective catalytic reduction). To learn more about how SCR works, you can read here.


AdBlue is a mixture containing 32.5% technical urea and 67.5% distilled water. AdBlue is therefore only the trade name held by the VDA (Association of German Automobile Manufacturers) for the AUS32 mixture (Aqueous solution of urea 32.5%) which must comply with the specifications of the ISO 22241 standard. It will be necessary to pay attention to this detail when it is necessary to top up AdBlue, because one brand is worth another, as long as it respects the aforementioned standard. Indeed, depending on the different countries, AdBlue can be indicated on the packaging as:

  • AUS32 (ISO 22241)
  • DEF (in America)
  • Arl32 (in Brazil).

Given that there is no AdBlue without SCRModern engines using this NOx reduction system also have a dedicated injector in the exhaust line. Based on the request of the engine control unit and within specific operating and temperature ranges, it is injected directly into the exhaust an amount between 3 and 5% of AdBlue compared to the diesel consumed. Because this is a reducer and non-additive, is not added to diesel, but has its own independent circuit. Activates the reaction of Reduction of NOx transforming them into nitrogen and water vapor in addition to other gases produced by combustion.


THE AdBlue consumption is so limited (we are talking about 1-1.5 liters per 1000 km) that do not need to be recharged as often. Depending on the car, the AdBlue tank can contain between 10 and 20 litres, therefore you will find different formats on the market, but pay attention to the price per liter of AdBlue which varies from 1 to 3 euros approximately, whether you restock it from the distributor or buy it in a box. Obviously, the larger the tank, the lower the unit price per litre. Here are some examples of AdBlue additives for sale on eBay at reduced prices from the best partner sellers of the platform:

PEMCO AdBlue Urea Diesel Solution in 20 liter can – eBay;

AdBlue VOLKSWAGEN GROUP – G052910M4 in 10 liter can – eBay;

Adblue BPR Chem Limax Euro 4 5 6 Vehicles with SCR technology in a 10 liter tank – eBay;

AdBlue Chimpex Urea Additive Euro 6 Diesel SCR with Spout in 10 liter can – eBay;

AdBlue Rhutten for Euro 6 vehicles with SCR technology with dosing spout in 5 liter canister – eBay;

AdBlue Lampa urea additive for Euro 4,5,6 vehicles with SCR technology in 5 liter canister – eBay;

AdBlue Lampa urea additive for Euro 4,5,6 vehicles with SCR technology in 1 liter can – eBay;


We talk about topping up as if it were child’s play, but isn’t it harmful to handle AdBlue? AdBlue can be handled without any particular risk, unlike the wax used with certain particle filters, which should only be handled by technical personnel and with care. For top up AdBlue simply locate the filler neck, usually next to the fuel filler but smaller, in the trunk or in some cases in the engine bay. But where is the adblue?? With the spread of more and more new cars with SCR system, it is easy to find AdBlue in any auto parts store. The driver always receives a message from the on-board computer well in advance when he still has approximately 1,000 to 2,000 km of range. Unless there is a problem with the AdBlue system.


To make life easier for drivers who are often on the move and unaccustomed to DIY and charging, there are many fuel dispensers who are equipped with specific pumps to fill up with AdBlue (see here the map of Italian distributors that supply AdBlue). If on the one hand the risk linked to the toxicity of AdBlue is almost nil, stinks, can stain clothes and damage paint. In addition, the -11°C freezing point already seems to have put a strain on frozen cars if the AdBlue tank is not properly insulated. Result: the car is blocked until the AdBlue solution returns to its liquid state.


Hello Franco, thank you for the intervention.
what you say is true, however both the price at the counter (which obviously also takes into account the costs of retail distribution and packaging) and that at the distributors are both variable and also depend on the cost of the raw material.

The vending machines displayed on the map belong to different logos, you can see this by clicking on them.
The most recent update is probably not included because the map, according to the site, is updated monthly.

Hello, advice: I topped up the expansion tank of the cooling circuit with 50% red paraflu and 50% demineralised water. The problem is that I confused demineralized water with AdBlue… is something going on? I topped up about 1 liter between paraflu and Adblu……help

It would be better to go to the workshop and have the cooling system drained when washing.

Source : Sicur Auto


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