Yeah... 192 gives more heat, but a 180 will give you heat faster in the mornings. I've tried them all, and I'll stick with a 180. At least when used on a V8. When I tried a 160, the air coming out was noticeably not as hot, I didn't like it. Using a different thermostat can sometimes confuse the vehicle's computer. Ditto on the some sort of problem. I'd check the hoses under the hood, to see if they feel warm. Wait for the radiator supply hose to feel warm at the top of the radiator. (Do not stick body parts into the fan blade.) If the supply and return hoses to the heater core are warm, the problem is probably under the dash, a blower door or something. If only one hose is warm and the other cold, the heater core isn't flowing any fluids through it. Kinda rare, but it happens. If you spilled even a small amount of anti-freeze, you would probably smell it. But if the smell was there before, you might want to find the leak before it gets worse. It seems that anti-freeze leaks seldom get better.