What is Fuel Additive? What Does It Do?

Thanks for the information, teacher. I advise me to use it other than wurt.

I also use a wurth at 10000. Once, my car had an injector error from dirty fuel. After throwing this out, the vehicle has reached 200000 for 4-5 years. C3 1.4 hdi

Now let's say we added this to half a tank of fuel. How long does it take to go and how long should I go after adding it? How much should we add?