heavy duty diesel

AdBlue (DEF) confusion mostly stems from how SCR works; it is not a fuel additive, never enters the engine, and—used correctly—cuts NOx without harming performance ^[3][4][1][2].

Disclaimer: Always follow the owner’s manual and ISO 22241 requirements; never dilute or add anything to the DEF tank, and use only compatible materials and clean equipment ^[5][6][7].