Ecoblue is the AdBlue manufactured by Cepsa. It is a synthetic product consisting of a urea solution in water that reduces emissions in light and heavy vehicles.
It is a product specifically designed for vehicles with Selective Catalytic Reduction technology. Ecoblue is not added to the fuel tank, but rather it reacts in the catalytic converter with the gases generated during combustion, converting nitrogen dioxide into pure nitrogen and water (steam).
Every vehicle using AdBlue has an auxiliary tank in which the additive can be refueled at service stations that now offer it together with the fuel, either in drums or bottles or both. Each car must be fitted with a sensor that monitors the amount of liquid remaining and when it needs to be replenished.