Something I have learned the hard way is that messing with the cooling system sometimes leads to other problems. I don't know what the treatment actually is, I would suspect a more concentrated version of the components of antifreeze, maybe a seal conditioner and stop leak compound. GM puts a sealing tablet in every new vehicle, they claim in TSB's that it is not required when changing or adding coolant. I have seen more times than not after a major drain or flush you can almost count the days to when a pump or some other cooling component starts to leak. If that stuff is a seal conditioner and stop leak compound I would use it, otherwise stop in any GM dealer and pick up a new sealing tablet and throw it in. In lieu of that just add a bottle of Bars Leak.