Thanks Pete! 
Results of the poll were: it will last 62%, it won't last 38%.
Congratulations Now that did not hurt did it.?
So what if it does not last ? stick another bottle in to hell with the expence.
Next time you will have a bit more confidence, I have no dought that it will last, I only used half the bottle the other half is in the back.
Now the acid questions, what does the car run like, would anyone who did not know what you used suspect a head gasket.
I bought mine as "head gasket gone" but after following this forum and one from the other side, for a very long time before i bought one, I was confident because everyone agrees it is a very vey rare event, who was it who said that with yours it was only the second one he knew of, on that basis alone it would have been a mistake to have rushed in and changed them at present. Without proof positive.
Now at your leisure you can check a few other things out, whilst using it.
The 38% wont's will be made up of change the parts for new, correct me if I am wrong but isnt that what the modern so called "mechanic" does. GM's bottom line does very very well, but without my and a few others on here's help.