Motul System Keep Clean Gasoline is a 300ml petrol fuel system treatment poured into the tank, intended as ongoing maintenance rather than a one-off decoke. Injector nozzles, intake valves and combustion chamber surfaces accumulate deposits over normal running, and even modest fouling upsets spray pattern and airflow, which shows up as rough idling, hesitation and a slow drift in fuel consumption. A detergent treatment used regularly keeps those surfaces clean rather than trying to recover them after the fact. Add it to the tank before refuelling so it mixes properly, and follow the stated dose for your tank capacity. This is the petrol version, so use the diesel equivalent in a diesel vehicle.