Complete Fuel System Cleaner (Diesel) is the most advanced STP fuel additive available for diesel engines. Proven on the road and track, it contains a complex blend of active components, designed to maintain diesel fuel systems in optimum operating condition. One treatment will help restore the vehicle fuel system to optimum operating condition by removing power-robbing deposits from the system. It is ideal for use in all diesel engine types including DI, IDI & Common Rail systems, that run on regular or biodiesel. Safe for FAP filters.