Originally Posted by KhanTyranitar

I have never seen a Motorcraft part made in China. I have seen many made outside the US, namely Mexico, Brazil, Germany, and England. I have never seen one from China.

China CAN make good parts, but you have to emphasis the CAN. In order to get good parts out of China, you need a quality control agent on site to oversee stuff, because of the ethical structure in China, money and profits are everything to them, and if you don't supervise and leverage them, they can and will cheat you. To leverage them, you just have to enforce that if they do not do exactly as instructed, you can easily replace them. I have dealings with China through multiple venues, so I know this directly.

In the case of thermostats, it does matter, a lot. Price is not the issue. I have bought Stant, both cheap and expensive, they don't work, Napa doesn't work, generic doesn't work. Every single non-Motorcraft thermostat I used in one of my Fords, and I have literally used everything out there, either did not last long before it either failed to open, or opened prematurely. Simple fact of the matter is that the aftermarket thermostats I have seen and tested do not open at the rated temperature under pressure. They open at the right temperature in a pan of heater water, but that is not a pressurized cooling system. When you put them under 15 psi pressure, they will usually start opening much sooner than the factory 192 degrees. Try opening at 160.

Every single time I decided to try my luck with an aftermarket thermostat, I was reminder why I fell the way I do about them. Every single time I then spend only a couple extra dollars to put the right one in, and I NEVER have an issue again. I've had similar experiences with fuel pumps, power steering pumps, and starters. I have had good luck with aftermarket alternators, suspension parts, transmission parts, etc. But the other parts I used were advertised as better than OEM. As far as who makes Motorcraft thermostats, based upon a trend I have seen in many Ford cooling systems, I suspect that AC Delco makes most of Ford's cooling system components.

In my case, a part that might last you two years will last me about 3 months, I drive about 40,000 miles per year, and I NEED reliability. Repairs and downtime cost money, a lot more than good parts do. If you don't want to pay dealer prices and you aren't in a hurry, you can get genuine Motorcraft online for reasonable prices.