Hey there possible outbacker. Sorry to hear about your issues with the car. I have been the happy owner of a 2000 OBS myself and the issues you raise are valid across the board. The head gaskets for the phase II engines were a known problem but there was no warranty that Subaru put out to recall all of them due to sheer volumes on the market. They seep oil and coolant. I know this because my 99 RS had the same SOHC engine and suffered the same leaks. The coolant conditioner that you talk about is Subaru's branded radiator stop leak, like a BARS product. It's only a bandaid for the situation. If you are getting bubbles in the radiator when you get on the accelerator then as much as I hate to say it, you might have a bad head gasket. This would contribute to the misfiring in cylinder 3 as well.
I wish you the best on getting your issues squared and my best to you with the weather situation that you all are enduring on the east coast.
I wish you the best on getting your issues squared and my best to you with the weather situation that you all are enduring on the east coast.
