Looked at a 99 forester, 107k miles; drove it over 20 minutes, no overheating; sounds fine but the radiator cap is cold even after driving and possibly some evidence of stop leak inside the cap; what do you think? run away asap or drive it again; add coolant and watch for bubbles?

Phase-II engines don't overheat unless run low on coolant. They leak externally - they don't push exhaust into the coolant. The stop leak is Subaru coolant conditioner which is probably keeping the drivers side head gasket from dumping coolant on the ground. At 107k its not a matter of if but rather when it will need them replaced. The answer is to use the EJ255/257 turbo head gasket - these don't exhibit the leaking symptoms.

 

GD

Phase-II engines don't overheat unless run low on coolant. They leak externally - they don't push exhaust into the coolant. The stop leak is Subaru coolant conditioner which is probably keeping the drivers side head gasket from dumping coolant on the ground. At 107k its not a matter of if but rather when it will need them replaced. The answer is to use the EJ255/257 turbo head gasket - these don't exhibit the leaking symptoms.

 

GD

 

I owned a 99 Forester, which I drove for 200,000 miles without any leaks or head gasket replacements. Maybe I'm just lucky.