Before buying: Turn head

First the basics:
The Ceratec was my Opel engine (1.6 l; 106HP; 148tkm) added, the ansich going very well, a little grinding noises were (last oil change before about 13tkm). To only be able to assess the impact of Ceratec, no oil change was performed.
Result: After about 700km now the grinding noises are as good as gone.
A positive influence on start behavior (previously no problems), refinement, throttle response and fuel economy I could not find, but I did not even expect. Thus, there is of me 5 points, it is an additional and not a panacea.

Now to the product itself:
First you should thoroughly research, and then to be able to separate truth from myth.
In addition, basic understandings of oils and additives should be present.

When adding products such CERATEC cheap oils with few additives, the effect will certainly be stronger than in quality oils with a high additive addition.
Each time the engine / transmission of the wear condition is depending on the mileage, load, maintenance etc. differently, so that even an additional as CERATEC different effects.
And one should underestimate the experience of the users neither too difficult nor too. I have professionally much to do with engines, but I do not trust to / be able to determine consumption in my private car engine (generally in good condition) an improvement in terms of refinement / throttle response. They would have been filled with it 4-5 motors.
The start behavior is also heavily dependent on the outside temperature.
One user (like me) felt no improvement in throttle response, the other user already. But that is highly subjective depending on: "I've used it, it must bring what, the engine now runs better" or "What should change already by 300ml broth, the engine is running now still as before."

Although CERATEC friction in the engine lowers, and that should logically reduce consumption, so are still the drag coefficient, the weight and friction of transmission, drive train and tire constant. Consumption will therefore, if any change, only the decimal. This, of course exactly the same test condition before and after the addition of CERATEC display properly.
If there is now talk of fuel savings of 0.5 l and more, so you should think strongly critical.
And otherwise: That would perhaps also have been possible with a simple oil change?

Where to eat Looking for Hestellerfreigabe:
Whether it works or not, no producer will ever release such additives.
This is not necessarily the fact that the manufacturer in relation to the positive effects (department conspiracy theory ...) balk, but that you simply can not assess the long-term effect and therefore the impact on the motor (liability volumes in case of damage).
There are now so many oils and supplementary products, engine and oil manufacturers test of consuming a few oils and can provide precisely what approvals.
Everything else is done at your own risk. Or someone brings a 7-digit amount and causes a long-term study.

One must also understand that the manufacturer, eventually someone is having engine trouble on the shop floor because he has heard that old frit oil lubricates as well as expensive full synthetic oil.
In a 0815 engine with little residual value as my a test of Ceratec is quite possible when the engine is still significantly more valuable (performance under 100tkm or in the warranty period) and primarily runs smoothly, I would probably not apply. Better to 5 spend more on high-quality oil (although I also use always quality oil).