Start-stop is a system which cuts a petrol or diesel engine when the car is stationary, in order to reduce fuel consumption and emissions. When the brake is released, or the clutch is engaged and the driver is ready to move again, the engine starts. A normal car without automatic start-stop can be expected to go through up to 50,000 start-stop events during its lifetime. However with automatic start-stop being activated every time the car comes to a standstill, the figure rises dramatically. The repercussion of this is start-stop engine technology is more susceptible to deposit build up. Once deposits have built up in the fuel intake system, the owner-driver of a vehicle with a start-stop engine will experience; power loss, driveability issues and exhaust emissions. STP® Start-Stop Diesel Engine Cleaner , specially formulated to help start-stop engines run better for longer, cleans and protects key engine parts, keeps the fuel intake system clean, assists with saving fuel and reducing emissions. DIRECTIONS: Simply add to your fuel tank every 2000 miles.