Diesel fuels combustion at different speeds depending on their quality, Itâ??s combustion speed is called the Cetane number. A higher Cetane number means better quality fuel and increased performance. Bio Mileager Cetane Booster maximize performance by increasing your dieselâ??s Cetane number by up to 2, so no matter what you put in your vehicle, you will be sure that it is receiving the best. Add to a full tank of diesel and use regularly for best results.