In a ZEX14P engine (Opel Corsa 2002), after 600km since the product was added, the noise (tap tap tap) from the lifters was reduced. It doesn't work miracles, it simply softens the noise, so it does indeed create an extra lubricating film. Don't expect to buy it and avoid repairs; it will just help to calm the noise in the engine and make it run better.

It does what it says and helps a lot to clean the insides of the valves (as much as this is possible without disassembling them) and definitely reduces their noise significantly.

I don't know what the mechanics say about additives; some say stay away, others say use them... abroad they use them a lot... but... after a few months of having it in the engine, I've heard the lifters knocking another 4-5 times, but most of the time they are quiet. Conclusion: for the money, it's okay, it does what it says, but it is a temporary solution, a patch as we say... it would work well for a smaller problem, if the lifters are not too noisy or if they make noise once and then are quiet, that’s where it would actually do a perfect job... despite this, I am not a mechanic, but to save money on opening the fake cover and changing the lifters... I suggest we initially change the oil (and the filter, of course) with a slightly thinner one than we usually use

Unfortunately, in my case, it didn't work. I have done over 1000 km and the noise remains. Fiat GP 1.4 95

In an old Seat Ibiza 1.2 car from 1991, the suspension was making noise. Sometimes the noise would stop. I installed this product and so far (about 6 months) nothing has been heard.

The sound of the engine has changed for the better/softer, however the oil overall seems to need a change earlier, already at 8,000 km after the previous change and 8 months later it appears darker than what Motul 4100 had accustomed me to in the last 3 years with annual changes at ~10-15,000 kilometers.

I made frequent short trips last winter and after a few kilometers, the car made a noise, the engine was "tak tak tak" at idle and when I increased the revs, it became louder and louder... I went to 2 workshops and both told me it was a stuck valve stem... I used this excellent product and after 500 kilometers, it really worked its magic and all the noises in the engine stopped!! From me, 5 out of 5!!

UPDATE: After almost 2 years, the valve stems were never heard again!

For optimal results, after an oil change, I applied it preventively at 40,000 km on a diesel vehicle, it stops the "rattling" of the valves and cleans the hydraulic tappets.

It has a fairly satisfactory result in rattling but it needs frequent use, every other change at most. Relatively expensive.