Diesel System Cleaner removes operationally caused contamination sustained throughout diesel engines' fuel system from the tank to the combustion chambers. It removes resin deposits, releases sticking injection nozzles and injection pumps, removes carbon residues and soot deposits within the entire upper cylinder area. It also lubricates and protects the diesel injection system and the whole upper cylinder area. Further, the product prevents the oxidation of the fuel and the growth of microorganisms. The fuel atomization is improved.