I gave it a 3/5 rating because I used it for maintenance without any issues and without seeing any difference in consumption, etc. The only thing I noticed is that the car was jerking even when the ratios of the additive were lower than what it was supposed to have to function. Other brands for the same product seemed to work better to me.

The Protec P1180 was used on a Fiat Punto Evo 1.4 (2010-120000km) & VW Passat 1.8T (2005-180000km) after an oil change using the Protec P1001 for internal engine cleaning and then the Protec P2233VIC was also used. The engines in both vehicles purr differently and you can immediately tell. The Fiat had a problem with the multiair system and the dealership was asking for 1800€ for repairs, but a used car dealer recommended these products to me because he uses them too, and yes, the warning light on the Fiat went off, no problem.

I use it to clean the valves and injectors of the engine, it does a noticeable job... It's a bit more expensive than the others but it's really worth it.
Usage instructions:
Add the product every 6 months to the fuel system before refilling with gasoline. Sufficient for 60 liters of fuel.

It simply does what it promises. It stopped immediately as soon as I put the additives and the engine works better. My car is a Ford C-MAX 1.6. Generally, in order to notice a difference, the engine must have high compression, for example, 11:1 and above, whereas in engines with lower compression, just a regular 95RON gasoline is enough.