Hi all.....we bought our 07 LT in 07 w/2200 miles in South Dakota.
it just turned 6600 and the heater core went out..
the thermostat failed aprox 3 months ago and I saw a milky white mixed w/antifreeze w/I changed the thermostat.
I ran flush threw it and changed antifreeze 3 times until it appeared like just antifreeze.
now I am needing the procedure to change the heater core "ie" safest way possible.
has any one had this happen to them?
thnxs....... scott.

 

heater core, I can't help with that, but it sounds like you have a bad head gasket and the antifreeze will turn milky again until that is corrected.

 

4400 miles in 5 years? Things are drying out.

 

If it is only 6600 miles, that could be the problem. Not being run and driven much, the fluids don't get to circulate. Sounds like lack of circulation has let the heater core corrode inside and start leaking.
IIRC, the dash has to be removed to gain access to the heater core(not 100 percent sure on this). Maybe ChevyMgr or someone else will see this and confirm it. Either way, it is a very labor involved job.