It's probably worth doing a search as this subject has been covered before in some detail. There are some interesting artilces that refer to class action law suits against some companies that make products such as this one that in reality do nothing for ones engine/transmission. Some even think that they do more harm than good.
I wouldn't put anything like this in my car. I have, though, used BG 44K added to my fuel to clean the injectors and lines. It is very expensive, but came highly recommended on the net. It is, though, bloody hard to find. I wouldn't bother with any other products, and I won't be seeking out the BG44K again for a while at the price it is today.
JH