AdBlue
AdBlue, also known as Diesel Exhaust Fluid (DEF), is a solution of urea and deionised water injected into the exhaust of modern diesel cars to neutralise nitrogen oxide emissions.
What it means
Modern diesel cars (most Mercedes, BMW, Audi, Volkswagen diesel models from around 2014 onward) meet emissions standards with a Selective Catalytic Reduction (SCR) system. The SCR catalyst needs AdBlue, an aqueous urea solution, sprayed into the exhaust upstream of it. The urea breaks down at exhaust temperature into ammonia, which reacts with nitrogen oxides on the catalyst surface to form nitrogen and water. AdBlue is consumed at roughly one to two litres per 1,000 km depending on engine load. The car carries a separate AdBlue tank (typically 12 to 25 litres) with its own filler usually next to or under the diesel filler. When the AdBlue tank gets low, the car warns the driver. If the tank runs completely dry, modern emissions regulations require the engine to enter a no-restart limp mode until refilled, since running without AdBlue would put the car out of compliance. AdBlue is widely available at fuel stations and as bulk containers for top-up at home or workshops.
Why it matters in Singapore
Singapore's diesel-car owner base is smaller than the petrol base, but for those with modern Mercedes, BMW, Audi, or VW diesels, AdBlue is a practical reality. Running out unexpectedly is one of the more avoidable inconveniences in diesel ownership, and the no-restart rule means it has real consequences.
How Revol Carz handles this
Revol Carz Garage refills AdBlue at every major service for diesel European cars, inspects the SCR system at the same visit, and stocks AdBlue for top-ups between services.