I add it preventively, every 3-4 months. I can't judge how effective it is but the engine has never shown any problems.

Logically, judging from experience with other products of the company, it is special. However, specific products have a usage limit of either 18 months or 24 months from their production. Has it ever been produced here and when does it expire or has it expired? I called the dealership and they didn't tell me, I sent an email, days and days passed and they didn't respond to me... should I use it or should I go to another brand that I know if the chemical is within the usage limit and of good quality?

I use it as a preventive measure, for its antifungal action due to the mandatory presence of biodiesel in diesel fuel. I want to believe that it does the job. I didn't have a problem to confidently say that it works. Anyway, many dealerships recommend such products.

I used it after being encouraged by the team, on a 1.5 TDCI, 120hp Ford engine, which I had never had any issues with for 70,000km. What I noticed is that the engine vibration at idle significantly decreased and its operation became smoother, especially at low speeds. I only use Shell V-Power Diesel and I believe it helped. I didn't see any difference in fuel consumption, only in the performance. Additionally, a positive aspect is that it has its own meter and you can calculate the amount you will use. Only time will tell if all these extras actually work, as I didn't have any problems before. The tangible result is the smoother low-speed engine operation, which is why I give it 5 stars. I didn't expect it to do anything else, that's its job.

I used it preventively (I changed brands now), I don't know how effective it is, on the positive side I will mention the dosimeter.

It seems to do the job.
In the Alfa Romeo Mito, where the engine trembles as if it's losing power on the second use, the engine behaves much better

In every 3 refills (3 months), I use it as a preventive measure to avoid dirt and fungi accumulation in the filter and pipes. The dosage is 10ml for every 10 liters. It also has an indicator, meaning that when you fill the bubble, if you have a 40-liter refill, you will add 40ml.

The rating is approximate because we are not evaluating something tangible, the installation of the add-on does not make our car a "plane" so that we can say "wow", it is something that will be more evident in the long run.

Although I am a supporter of Wurth, I don't know what rating to give you to tell you the truth. I put it in my 2014 Mercedes and I can't say that I saw any difference. That's why I gave it three stars. I don't know if it's fair, but as I said, I didn't see any difference. Of course, I don't know what difference I should have seen. My mechanic, however, has told me that if I want to use any cleaner or additive, I should use Wurth. It's one of the best. I have tried a cleaner that really works. But as an additive in the fuel tank, I didn't see anything. Sorry, Wurth

I have been using it in my Opel Corsa C 1.3 CDTI 2004 for 2 years, filling up approximately every 3 times with only Shell V-power diesel (around every 2500-3000km). I haven't noticed any significant difference in fuel consumption or performance. I use it as a preventive measure and have never had any issues with the fuel.

Read the instructions and don't listen to what everyone says.
"Instructions for use: Add the product to the fuel tank (regularly every 3-4 months), before filling with diesel and biodiesel fuel, in a ratio of 1:1000 (0.1%)".
So, if the tank is 50 liters, you add 50ml, 60 liters 60ml, etc

Extremely effective biocide at €9.20 that I bought. I add VPOWER fuel and also added the specific one they recommended at the gas station. Add the product to the fuel tank (regularly every 3-4 months), before filling it with diesel fuel and biodiesel, in a ratio of 1:1000 (0.1%). So if you put in 40 liters, you should add 40ml.

Very good, and obviously with a strong recommendation. With one filling, you pour 25ml into the dosimeter it has, every 2 fillings, and it cleans the residues of the biodiesel. Especially if you use it from the tank, you should use it.