what is the stock temperature gauge in the dash for? is the the air temp gauge or water temp gauge???

 

water

 

so does that mean that an aftermarket gauge would be useless?

 

WOW, just WOW.

 

The stock gauge measures water temperature, but is not overly accurate. It is very close to being a 3-way switch - cold, normal, and hot. This is because the average consumer apparently is freaked out when this gauge moves around showing the actual temperature variance. An aftermarket gauge will accurately show the temperature and has actual numbers for the temp.

 

an aftermarket water temp gauge will be more accurate and let you know whats going on. The stock one is pretty much useless as far as accuracy goes.

 

You're all wrong.
That's the outside air tempature indicator so you know when to use your air conditioning.

pffffft jhhahaha I'm sorry
(turbohappy's answer is perfect)