So my car gets up to normal running temperature and stays for about 5 minutes of driving. Then within about a minute it goes up to just below the red lines on the temp gauge. It stays there for about 5 minutes and then goes back down to normal. After that, every minute it goes up then down again.

I changed the thermostat thinking maybe iot was just sticking but no luck there. I noticed a a wire coming out of the metal tube that the thermostat housing was bolted too. Where the wire went into the metal part was all green and corroded. I dont have a clue what that is tho.

Also, when i had almost straight water in the car, it was boiling out of the tank when i took the resevoir cap off.

I dont know what to try doing next. Im not very knowledgable on car stuff so any help would be appreciated.

Thanx,
Ben, saint louis

It is possible to get a new thermostat that is bad. Has happned to me several times. Make sure you use a new gasket. You could try exchanging it for another, or drop it in a pot of boiling water to see if it opens and closes.

You never want to use 100% water or 100% antifreeze...follow the manual or do 50/50. You should also try to use distilled water if possible because tap water contains minerals that can clog the cooling system.

+1 if i am not mistaken, the wire is part of the sensor, so a corroded one will not conduct a correct signal.