The chemical is dynamite. Excellent for addressing a problem at the beginning (light tap on the injectors, prevention) and easy to use. Within one tank and after 800km the sound changed and I avoided having to fix it

2 pieces were used over a range of 4500 km, after a recommendation from a mechanic, due to partially reduced performance of the diesel injectors.
There seems to be a slight improvement in the vehicle's performance, which may possibly be attributed to this product.