I know this thread is a little old, but may aswell still give my input
As its already been said, your temp gauge on your dash cluster is you water
I would go with Oil Temp and Oil Pressure
Who cares about battery?? if it goes it goes, buy a new one lol
Just my advice, as I am putting some in my calais, but no on the dash, im putting mine on the side pillar on the drivers side