Stumbled across this forum during a google for thermostat related items. Just a note of Thanks. Would have never figured thermostat replacement needed something beyond a replacement item. Especially the burping stuff and adding antifreeze through the upper hose. Until I added antifreeze through that upper hose, the car was still running way too hot. Now it seems just fine, temp where it should be and heat working well. I was thinking Subaru's are different since the thermostat is on the bottom Vs. the top on every other car I've had.
