[cardoc]

Are you checking the coolant level by removing the radiator cap? It sounds as though the coolant is low and there isn't enough in the engine to push through to the core. Just because there may be coolant in the resevoir does not mean there is sufficient coolant in the radiator and engine.

Now that it has run hot, you need a thermostat. The engine needs to be checked for signs of a coolant leak. If you can't find the leak, replace the radiator cap when you do the thermostat. The thermostat is easy to change.

Be sure to get the thermostat from Subaru. It comes with a seal. Get the cap from Subaru or any parts retailer. Use good coolant and no tap water. Be sure to "burp" the system when you refill it by leaving the cap off the radiator through a few thermostat cycles.

 

[cardoc]

I would bet that when the radiator is filled the leak will reappear.

Check the heater hoses running from the rear of the engine for wear/leaks. They will drip onto the exhaust. Look on top of the engine for puddled coolant that would run down the back of the engine.

If you can't see a leak, it may be a good idea to have it pressure tested.