Does the reservoir tank get filled to top with coolant in 2006 Chevy Impala?
No, the reservoir tank in a 2006 Chevy Impala (or any car for that matter) should not be filled to the very top. It needs headspace for expansion as the coolant heats up. The reservoir tank will have minimum and maximum fill lines; fill it to the "cold" or "low" line when the engine is cold.