Diesel Fuel Supplement +Cetane Boost is an anti-gel/winterizer that is used in the cold winter months to keep fuel-filters from plugging with wax and to prevent fuel gelling. This Arctic formula effectively treats all diesel fuels to keep equipment running trouble-free for maximum winter operability. Diesel Fuel Supplement is intended for use only during cold winter months when temperatures drops below 30 degree Fahrenheit. Use Diesel Kleen +Cetane Boost for peak performance in non-winter months. If your vehicle does not start or gain power in cold temperatures, use Diesel 9.1.1 as directed on the container label.