Quote:Really?!? I've owned quite a few cars in my life and have never had that happen to me. Although I have never used a stant brand thermostat. That doesn't seem like it would be a good thing to me.
Every brand new stant I've put into my Dad's Blazer overshoots then returns to normal.
Quote:Learn something new everyday. However, if this is a new behavior I would throw a new thermostat in there. It probably needs replacing by now anyway and we aren't talking a lot of $$ here. Should be easy to do on the Mazda.
My chev k1500 used to overshoot at about 3 miles then drop to a mid-cold level. The needle would then go up and down like this a few times (dropping to a higher low-level each successive time) until it would settle at and hold the final operating temp. I think this would be pretty normal if you have a large radiator with significant cooling capacity. The cool water from the radiator really makes a significant temp differential the first few times the thermostat opens. I think this considered normal for many cars.