adBlue: What you need to know about the diesel additive

photo: total

The euro 6 emissions standard has been in force since 2014. To meet the new limits, many diesels have to be refueled with Adblue. What’s behind the additive? Company car clarifies.

Drivers are already confused at gas stations: ultimate, V-power, maxx motion or fuel save – at most, only the regular customers of the respective mineral oil companies know at once what they are filling up their tanks with. Now comes another tap with the beautiful inscription adblue into play. Here, too, the marketing experts have tweaked the name. Because it is actually a urea solution, as it is used, for example, in numerous hand creams – also better known as urea. In diesel engines, adblue ensures that the nitrogen oxide is almost completely converted into harmless nitrogen and water.

32.5 percent urea solution

Since september 2014, new emission limits have come into force with the euro 6 standard. Instead of the euro 5 standard, nitrogen oxide emissions are to be reduced from a maximum of 180 milligrams per kilometer to a maximum of 80 milligrams. Initially, the new directive only applied to new type approvals. Since 2015, however, all new cars have had to comply with the stricter limits.

While nox storage catalytic converters are sufficient for smaller vehicles to meet the euro 6 standard, the larger models require an SCR catalytic converter (selective catalytic reduction). The 32.5 percent urea solution is injected into the exhaust tract directly upstream of the catalytic converter from a separate tank.

Adblue has been used in trucks for some time now

Adblue itself is nothing new. The additive has long been used in trucks to reduce nitrogen oxide levels in commercial vehicles. A truck driver expects adblue consumption to be about five percent of normal diesel consumption. For a heavy truck, this corresponds to around 1.4 liters per 100 kilometers. The adblue network for trucks is correspondingly well developed. However, due to the increased flow rate of truck dispensers, they are not suitable for passenger cars. At four shell service stations (ingolstadt, munich, sindelfingen and wolfsburg), the additive for exhaust gas aftertreatment is now also being offered on a trial basis for diesel passenger cars at dispensers.

Adblue is topped up at the service station

For passenger cars, manufacturers calculate around 0.1 liter of adblue per 100 kilometers. According to plan, the urea solution is to be added by the workshop during regular maintenance. That is, after about 20.000 to 30.000 kilometers. And for emergencies, the urea solution is also available in bottles in the gas station stores between the engine oil and windshield wiper fluid.

Why the pilot project with the adblue dispensers?? There are currently around 200.000 diesel cars and vans with SCR technology on the road in germany, but by 2020 three out of four new cars with compression ignition engines could require an adblue supply. Shell and the manufacturers audi, BMW, mercedes, porsche and VW would therefore prefer to use this pilot project to start coordinating the technically different refueling systems of the manufacturers with one another today. Advantage for us customers: we then have enough time to get used to the nice new name.


Functional principle of SCR technology: adblue is an aqueous urea solution that is carried in an additional tank. During operation, the engine electronics control the dosage so that the harmful nitrogen oxides contained in the exhaust gas stream always meet the right amount of reaction partners. The water-dissolved adblue is injected into the hot exhaust gas and hydrolyzed to form ammonia (NH3), which then triggers the reduction of the nitrogen oxides to harmless nitrogen and water in the downstream SCR catalytic converter.


Ten questions Ten answers

What is adblue?
An aqueous urea solution that reduces the nitrogen oxide content of diesel engines by 90 percent.

Does adblue have other advantages?
Yes, fuel consumption drops by up to five percent.

Where adblue is found?
In a separate tank, usually in the spare wheel well.

How big is the tank?
Between 20 and 30 liters.

How long does the tank last?
20.000 to 30.000 kilometers. On average, 0.1 liter of adblue is needed per 100 kilometers.

Do I need to top up with adblue?
Normally, the tank size is designed in such a way that the manufacturer refills it himself during the inspection. Should it be emptied beforehand, either via a tank nozzle or a special access point in the trunk.

Will I be warned before the tank is empty??
Yes, the on-board computer indicates this in good time.

Can I drive without adblue?
Usually not. It is then no longer possible to start the engine.

Where can I get adblue?
At car dealers, accessory stores and also at many gas stations. They now even have their own dispensers. But be careful, some are only suitable for trucks.

How much does adblue cost??
Generally, the larger the canister, the cheaper it is. Online, 40-liter canisters are sold for around 30 euros gross.

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