Diesel Kleen +Cetane Boost is a technologically advanced diesel engine performance improver that cleans injectors, boosts cetane and lubricates fuel injection components. This maximum horse power formula restores lost power, smooth rough-running engines and improves fuel economy up to 8 percent. Diesel Kleen can be used year around, but it is not a diesel fuel winterizer or anti-gel. When winter temperatures drop below 30 degree Fahrenheit use Diesel Fuel Supplement +Cetane Boost to provide maximum winter protection for your diesel engine.