Diesel Fuel Supplement +Cetane Boost (in the white bottle) is a winterizer/antigel for use when temperatures drop below 30°F. for winter operability. Diesel Kleen +Cetane Boost (in the silver bottle) is an injector cleaner and performance improver for use when temperatures are above 30°F. Use our seasonal tip to help remember which product to use: “White for winter, silver for summer.”