STP DIESEL PARTICULATE FILTER CLEANER: It's cheaper than a mechanic! STP® Diesel Particulate Filter Cleaner is designed to remove soot particles and carbon from diesel particular filters. One treatment helps unclog filters, removing accumulated unburnt soot to regenerate the DPF, perfect for stop/driving styles such as city driving, taxis and those that use their vehicle for school runs. All diesel cars manufactured after 2009 have a DPF fitted to the exhaust system which traps harmful soot particles from being expelled into the environment. Like most filters, a DPF needs to be cleaned regularly otherwise it will become clogged and your DPF warning light may come on and could resulting in a trip to the mechanics! STP® Diesel Particulate Filter is best used every 1800 miles as a preventative measure, however should your DPF light come on, give it a try before you visit the mechanics. IS IT SAFE TO USE IN MY VEHICLE: STP® Diesel Particulate Filter Cleaner is suitable for diesel engines with a standard built-in or retro-fitted diesel particular filter. Not recommended for heavy duty trucks with continuously regenerating traps.