Despite its misleading name, AdBlue is not actually a blue liquid, but rather colorless. It is neither a fuel nor an additive.
Instead, it is a fuel-complementary product designed to reduce polluting emissions from modern diesel vehicles. Biodegradable, non-hazardous, and colorless, AdBlue is primarily composed of demineralized water mixed with high-purity urea, as regulated by ISO 22241.

AdBlue is part of the SCR (Selective Catalytic Reduction) system. This system aims to reduce exhaust gas and NOx (nitrogen oxide) emissions from diesel vehicles.