I might be unfairly rating it and it may actually do a good job, but only in completely new cars. As soon as I put it in a vehicle with approximately 180,000 km, in which I only use premium diesel, after a few kilometers a warning light came on the dashboard and one injector was knocking. I tried it again after 5,000 km and got exactly the same results. It was also tested in another car with a lot of kilometers and after a while it struggled to start, and the fuel filter was changed, which had been replaced not long ago. Obviously, it works but only in new cars