Well to start off, my heat was a bit cold and it's really cold out. Its a 10 mile drive to work through the city so I figured it was normal for the heat to be a little cool. Someone told me to replace my thermostat so I did and now it gets way to hot. I have a digital gauge that tells me the temp and before I put it in it would get to about 181 F going down the highway. If i turned off the heat it would get to about 195-200 F. After the new thermostat it goes to about 215-220 F with the heat on full and when i turn the heat off it jumps to about 240 F and the needle on the dash is getting up past the half way. I've never seen it get that high, even sitting in traffic at 90 degrees out. So anyway I was a little low on coolant so I topped it off and its still gets very hot. The upper hose is extremely hot and the lower hose is ice cold. But AFTER i turn off the car the lower hose gets hot. even after driving 30 miles on the interstate. The radiator cap was slightly warm. I took it off right away with no problem. And yes I know you shouldnt do that, but there was coolant right to the top of the radiator but very little steam. It didn't make a sound when I opened it. I did go with an aftermarket thermostat.. Anyone have any suggestions? And can someone tell me what the normal operating temp should be?