The switch only flows in "auto" when your engine coolant temps reach more than 105degC. Even in autocross I've never seen the car get that hot, the fans kick in WAY before that. The only time the car actually got that hot was on the dyno.

So I would use it manually on extremely hot days, or on a track or the dyno. Otherwise just leave it alone.

Make sure and keep it topped up with water when you check the rest of your fluids. The reservoir is at the right corner behind the headlight when facing the front of the car looking into the engine bay.

 

You have about 2.5 gallons left when the light comes on.