Thermostat MISHIMOTO or AISIN

After doing some research I found that AISIN is likely the supplier for the Subaru OEM thermostats so I ordered them off of Amazon (sold and shipped by Amazon) and they appear to be just that. They were close to the same price and are made in Japan. AISIN THF-007/009 appear to be true OEM Subaru thermostats for FB20B

Pick up the AISIN OEM version of your thermostat. It's pretty cheap so no reason not to get the best one instead of some cheaper alternative. Also you can test the function of your thermostat before doing the change by putting it in hot water. You can check the specs of the one you use, but for the AISIN one for my 2012 civic (9th gen), the thermostat starts opening at 170 and is fully open at 190.

I still changed my thermostat to an Aisin unit for peace of mind, so far so good.

I just bought two thermostat related parts off rockauto that are both Aisin yesterday.

I have installed them in two rebuilt, and they are working perfectly fine

I wanted to upgrade from plastic and got an aluminum Mishimoto thermostat, but i didn’t notice that it opens at 180°. Can i get away with the 180° thermostat, or should i ship it back and re-order a different, higher rated thermostat?

I put the mishimoto 160* in hot water to test it out. Lo and behold, wax started seeping out.

I had 2 fail back to back. The first lasted 3 months, a couple thousand miles, the 2nd lasted 5 weeks, also a couple thousand miles. Left me stranded. 275 degree spike followed by coolant puking.

when installing a mishimoto thermostat, check that the shoulder/flange is the same thickness as oem. Otherwise your stock hardware WILL NOT FIT. You will bottom out the bolt in the timing cover and snap that mf. Those bolts are extremely hard to access and a MAJOR HEADACHE to get extracted.

mishimoto changed the design of the thermostat when I purchased and you will need shorter bolts they are not provided