Diesel 911 is a winter emergency use product. This Winter Rescue Formula reliquefies gelled fuel and de-ices frozen fuel-filters to restore the flow of diesel fuel to an engine. Diesel 911 does not prevent fuel gelling – use Diesel Fuel Supplement +Cetane Boost (in the white bottle) as a preventive measure to keep fuel from gelling. Diesel 911 and Diesel Fuel Supplement +Cetane Boost are compatible in diesel fuel and may be used at the same time. Reliquefies gelled fuel. De-ices frozen fuel-filters. Removes water. Prevents fuel-filter icing. Contains Slickdiesel Lubricator to protect fuel pumps and injectors from increased wear caused by poor quality Ultra Low Sulfur Diesel (ULSD) fuel. Effective in all diesel fuels， including ULSD and biodiesel blends. Safe for use in all diesel engines. Will not void engine manufacturer's warranty when used as directed.