Coolant Loss With No Leaks On The Ground

[Real time recon]

2002 Silverado 4X4 1500, w/150,000 miles stock factory 5.3L ,325 C.I. Vortec eng. W/ auto trans. This sucker is eating about 3 Qts. of coolant a year (2,500 -3,000 miles per year). And none is on the garage floor
What ya think ? A slightly blown head gasket ?
And IF so.Have you tried this stuff ? http://store.gobdp.com/head-gasket-sealer-38386/

 

[MustangIIMatt]

Go to Advance or Zone and get their cooling system pressure test kit from their loaner tools. Top off the coolant and pressurize the system and see if the leak reveals itself.

Do not put a stop/leak or sealer in a DexCool system. That is bad enough with old fashioned ethelyne glycol, it's an even bigger nightmare with an OAT coolant like DexCool.