Thermostat Wahler or AISIN

I just put a new Waller in every 8 to 10 years when it comes time to redo the cooling system. Never had a leaking or stuck thermostat but we do live in Southern California, so I think things tend to last longer Here

I've had a Wahler fitted for 1.5yrs and everything's ok so far

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.

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.

My 2007 MKV 2.5 Jetta is still having overheat problems even after changing the tstat to a OEM (Wahler) and the waterpump to one with metal impeller, which works way better than the original.

I’ve replaced it twice and it starts leaking from there in about 2000 miles or so. I’m willing to bet that thermostat is a Wahler brand. They are known to leak like this.

The wahler thermostat is either broken or its too cold where i live cause the car never really gets up to temp (or my temp sensor is broken).

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?

The Wahler one's are rubbish. Did the same after my fucking brand new Wahner DID NOT work....