Sodium silicate, look it up. It is the active ingredient (well, one of the active ingredients) in most of these "potions". It transforms into "glass" at about 115 degrees, and if you ask me, it is something that should just be added to the cooling system in our engines. I know that this is early days, but I can only say that my 1.8T is perfect.
The water loss that started to creep up on us lasted about 14 days before I added the stuff. It has utterly and completely cured the loss, and there has been absolutely no noticeable ill effects, whatsoever. In fact, I feel really good every time I check the water and see that it hasn't moved one mm!!
This has cost me the princely sum of about 5 Pounds! There is absolutely nothing that prevents me from ripping the engine out and overhaul it. But why?
The small clearance(s) that allowed water to pass the liner(s) has (have)been blocked and sealed with "glass". In all honesty, I think it works better than the seal from the factory.
If things gets out of hand, then you get to a point where only surgery will help. It is in any ones interest to prevent things from developing so far.
If I had not overhauled my V6 and locked the liners with Lock-tite, I would add the stuff to my V6 as a precaution. And I think this is really good news!
But time will tell, I will continue my updates, then you can decide from there.
And Dave, when you come to South Africa, come and say hello, if you get the time!