Despite doubts - it works!

I bought 2 boxes, but so far only used 1. The effect is sustainable and clearly audible.
As long as the agent in the tank, you can feel a reduced distance (I imagine). That lies down with the next refueling. And the effect was there. Rußte the engine before that and jerky, these were subsequently clearly there no longer.
I do not know how, but it was causing. Although I had previously doubted strongly.