mysterious coolant dissaperance..

[rbforsale]

welp,i have david copperfeild in cahoots with my engine ,cause coolant seems to disappear like magic..i have replaced the radiator,water pump,thermostat.ALL hoses,by-passed the heater core,compression tested,leak down test,hydrocarbon tested, coolant system tested, bled bled bled........where is it going?!?!? and the car gets hot at highway speeds,the moment i slow down so does the temperature,so my temp gauge thinks its the speedo. coolant level will drop rather quickly even as im putting fluid in it when its not running.checked for leaks multiple times...nothing.its a fresh rebuild with all new gaskets and hoses. its not smoking, or a sweet smell,oil is not milky or watered down....im at a loss fellah's. its an out of this world conundrum.

[MrSoutherland]

Maybe this is a silly q, but are you sure you filled it all the way?

[rbforsale]

im 100% positive that i filled it all the way

[rbforsale]

also,has anyone had a any bad experiences with auto zone or"stant'' thermostats? cause i think i may know what mah problem is..