I recently replaced the original thermostat in the Fusion. Using my Torque app, I noticed that the coolant temp would never get above the high 170s. As time passed, it almost never got over 170. OE thermostat temp is 190, and after thermostat replacement, coolant now sits between 190 and 210, depending on driving conditions.
My Sedona has the original thermostat also, which is rated to start opening at 180. Using the same app, I've noticed since I got the van that the coolant rarely budges above 177. It loves to sit there. Occasionally it'll bounce above 180, but then drops right back down. I ordered an OE/Aisin replacement and will report on the results. For the Fusion, restoring the higher (normal) coolant temps has resulted in better gas mileage; back to where it used to be.
My Sedona has the original thermostat also, which is rated to start opening at 180. Using the same app, I've noticed since I got the van that the coolant rarely budges above 177. It loves to sit there. Occasionally it'll bounce above 180, but then drops right back down. I ordered an OE/Aisin replacement and will report on the results. For the Fusion, restoring the higher (normal) coolant temps has resulted in better gas mileage; back to where it used to be.