It came from the factory with Dexcool. At the present there are several class action lawsuits against Gm for using Dexcool as it will get like red clay if subjected to air. I suggest you us the green antifreeze.
The 2001 Chevrolet Impala has overhead valves (OHV).
134a
The 2005 Chevrolet Impala has overhead valves (OHV).
The 2006 Chevrolet Impala has overhead valves (OHV).
The 2007 Chevrolet Impala has overhead valves (OHV).
The 2011 Chevrolet Impala has overhead valves (OHV).
The 2002 Chevrolet Impala has overhead valves (OHV).
The 2004 Chevrolet Impala has overhead valves (OHV).
The 2003 Chevrolet Impala has overhead valves (OHV).
The 2010 Chevrolet Impala has overhead valves (OHV).
The 2008 Chevrolet Impala has overhead valves (OHV).
The 2009 Chevrolet Impala has overhead valves (OHV).