vs
Thermostat AISIN or Motorcraft
Reviews
Your thermostat is probably stuck open. Replace it with an OEM Motorcraft version, not aftermarket.
Pros: OEM Motorcraft version
Cons: not aftermarket
Hard to say if it’s directly OE to Subaru, but I use Aisin thermostats and water pumps on every Subaru engine I do, they function the exact same and are equally as reliable as the original equipment, not to mention these thermostats are $15 on amazon compared to $40 from Subaru.
Pros: equally reliable, functions same as OE
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
Pros: true OEM quality, made in Japan
Part number: THF-007/009
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.
Pros: OEM quality, good value, accurate opening
Vehicle:
Honda Civic
The Motorcraft thermostat sounds promising though, never have an issue with genuine ford parts.
Pros: no issues, reliable
Vehicle:
Jeep Cherokee
I used a motorcraft RT-1139 thermostat. Comes with a jiggle valve to help bleed air already installed and cost me 8 bucks. You won’t find any place that says they fit other than some forum posts but they do indeed work, I installed one on my MJ with the only issue being me not refilling the radiator after dumping all the coolant.
Pros: works well, jiggle valve, good value
Vehicle:
Jeep
Part number: RT-1139
I requested they use only Motorcraft thermostat, because I knew there was a part # update. Threw the updated Motorcraft one in and it solved the issue.
Pros: solved issue, updated part
Vehicle:
Ford
New thermostat (Aisin brand), fresh oil, fresh coolant, replaced at that time. Coolant system bled well. No leaks. Heat worked flawlessly. AC worked after the swap. Overheated the drive home after that swap, turns out the radiator fan module got fried on the final drive (it was above 250 on coolant temps before replacing the engine, on a 30 minute, fast, highway drive). Ordered a new one. Everything working perfect now at the right temperature points. Engine times reading perfect too (watching live data). On a 30 minute highway drive tonight, returning home after the same drive 2 days ago with zero issues, it overheats again. Radiator fans are working. The one thing I changed during the drive was turning down the heat from HIGH to 75. No more than 10 minutes later I hear the bubbling in the heater core area. Take my exit from the highway, and the red temp light starts flashing, temps read 239, and the bubbling worsened. Temps stayed above 228 until I made it home from my exit. Worse at red lights. Turned off for 10 minutes, turned back on, temps went up to 232 at idle, holding steady. Lower radiator hose read 102 degrees, upper hose reads 190.
Pros: heat worked flawlessly, AC worked
Cons: overheated, bubbling in heater core
Vehicle:
Subaru Outback
I bought a Motorcraft thermostat from the Ford dealer for my Crown Vic and it ran about 20 degrees cold.
Cons: ran 20 degrees cold
Vehicle:
Ford Crown Victoria I
Aisin THF-003 thermostat was used (I believe this is what I'm regretting). It's like the thermostat isn't opening? Everything else seems fine - it's clearly getting hot. Little to no heat at idle. No circulation = overheating of the engine. Is the replacement thermostat stuck shut?
Cons: thermostat not opening, overheating engine, little to no heat
Vehicle:
Subaru Impreza
Part number: THF-003
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Which thermostat to choose — AISIN or Motorcraft?
If choosing thermostat across many manufacturers, check the part ranking. If your choice is down to two brands, the PartReview part comparisons help.
We compare thermostat across these categories:
- PR Score.
- Overall ranking.
- Vote balance.
- Average rating.
- Number of reviews.
- Feature ratings.
- Car owners’ choice.
Which thermostat are better — Motorcraft or AISIN?
In March 2026 on PartReview, thermostat AISIN were overall better than Motorcraft.
- AISIN received a PR Score of 83 out of 100, and Motorcraft scored 74 points.
- AISIN ranked 5 in the overall ranking, and Motorcraft ranked 8.
- The average rating based on reviews is the same for AISIN (4.3) and Motorcraft (3.9).
-
Thermostat AISIN have better feature ratings than Motorcraft:
- Slow warm-up - owners believe, that this property for AISIN is better than Motorcraft.
- Overheating - drivers claim, that this property for AISIN is outperforms Motorcraft.
- Cabin heat - reviews suggest, that this property for Motorcraft is preferred to AISIN.
Which thermostat are more popular — AISIN or Motorcraft?
In March 2026 on PartReview, thermostat Motorcraft were overall more popular than Motorcraft.
By vote balance, thermostat AISIN surpassed Motorcraft:
- For AISIN, the ratio of positive (26) to negative (5) votes is 21 vote.
- For Motorcraft, the ratio of positive (23) to negative (8) votes is 15 votes.
By number of reviews, the manufacturers are equal:
- For thermostat AISIN there are 10 reviews: 8 positive, 1 neutral, 1 negative.
- For thermostat Motorcraft there are 10 reviews: 7 positive, 1 neutral, 2 negative.
Which thermostat do car owners prefer — AISIN or Motorcraft?
In March 2026, according to PartReview, thermostat AISIN and Motorcraft have not taken top places in car-specific ratings. You can help by adding your review about these manufacturers.
Other comparisons of thermostat
If this comparison didn’t fully answer your question, there are many others on PartReview.
For example, comparisons of thermostat AISIN with: MotoRad, Wahler, OEM Volkswagen, Mahle, OEM Mazda, MOPAR, MISHIMOTO, Gates, OEM BMW, OEM Nissan.
Also available: comparisons of thermostat Motorcraft with: MotoRad, Wahler, OEM Volkswagen, Mahle, OEM Mazda, MOPAR, MISHIMOTO, Gates, OEM BMW, OEM Nissan.
You can also see who is better among other thermostat manufacturers: Wahler or MotoRad, OEM Volkswagen or MotoRad, Mahle or MotoRad, OEM Mazda or MotoRad, MOPAR or MotoRad.