What are the additives for diesel

Additive for diesel drivers: why they need to refuel with AdBlue

Diesel drivers only fill up with diesel? Sure, but some also need something else. Anyone who drives a diesel with a so-called SCR catalytic converter also has to refuel with AdBlue from time to time. What's this?

In order to lower the nitrogen oxide readings (NOx), a method that has been around for years in the commercial vehicle sector has now also proven itself in diesel cars: selective catalytic reduction (SCR). This is so because with this process, with the help of a catalytic converter, only the nitrogen oxides in the exhaust gases of a vehicle are reduced, explains Dekra.

To do this, you need an additive with the brand name AdBlue. But what is actually behind this name?

Chemical reaction for cleaner exhaust

AdBlue is a mixture of 67.5 percent water and 32.5 percent synthetic urea, which is continuously injected into the exhaust system from a separate tank and chemically decomposed by the hydrolysis catalytic converter, explains Dekra expert Erik Pellmann. In the exhaust system, the liquid then reacts within fractions of a second with the nitrogen oxides from the engine's combustion and converts these emissions into harmless water vapor and nitrogen.

The additive must not get into the diesel tank

"AdBlue is not a fuel additive and must never be mixed with diesel," warns Pellmann. There is a separate tank with its own filler neck in the spare wheel well, next to the diesel nozzle or in the engine compartment. The tank size varies between ten and almost 40 liters, depending on the car model.

Consumption is around three to five percent of fuel consumption. Depending on the coordination of the exhaust system, the displacement and the driving style, refilling is necessary approximately every 5,000 to 15,000 kilometers. Sometimes the tank contents last much longer.

A warning notice informs about the running out of stock at various intervals. If the sensor detects an empty tank, the engine can no longer be started - but only after several misfires. The engine control software takes care of this. A visit to the workshop is not required to refill; you can do this yourself with the help of a special filling hose.

more on the subject

  • Subjects:
  • Automobile,
  • Traffic,
  • Counselor,
  • Environment,
  • Diesel,
  • AdBlue,
  • Fuel,
  • Mobility,
  • Germany,
  • Engine,
  • Nitrogen,
  • Refueling,
  • Dekra