vs
Thermostat OEM BMW 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
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
I still changed my thermostat to an Aisin unit for peace of mind, so far so good.
Pros: peace of mind, good performance
Vehicle:
Lexus
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
Pros: perfectly fine operation
03’ E46 318ci with 130k miles and no issues with the whole cooling system. Neither the thermostat.
Pros: no issues, long lifespan
Vehicle:
BMW
Mileage: 209215 km
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
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
I replaced the t-stat with a genuine part and again no luck.
Cons: did not fix issue
Vehicle:
BMW
Changed to genuine thermostat, no change. Needle tends to dip on higher load highway driving, but only occasionally. Obd temp is between 77C-88C.
Cons: no change in performance, needle dips on load
Vehicle:
BMW
Write your review
Help others - share your experience with this part.
Comparisons
Show all
Voted AGAINST engine oil RAVENOL on the rating page
The brake pads NIPPARTS got the first review!
The brake discs Hella got the first review!
The brake discs OEM Suzuki got the first review!
For tires OEM Toyota already 25 reviews.
For tires IRONMAN already 25 reviews.
For starter motor OEM Volkswagen already 25 reviews.
In the rating best ignition coil already 13 brands participate!
In the rating best fuel pump already 5 brands participate!
In the rating best turbocharger already 4 brands participate!
In the auto rating headlights for Volkswagen Golf already 5 brands participate!
In the auto rating brake pads for Mazda 5 already 10 brands participate!
In the auto rating brake pads for BMW M2 already 5 brands participate!
Voted AGAINST engine oil RED LINE on the rating page
Voted AGAINST engine oil PENNZOIL on the rating page
