Originally Posted By: sw99
I use cheap old WalMart SuperTech green and now have over 177,000 on the car with no problems.
According to your signature, you have a 2.2L, therefore you will have no problems. This applies to the 2.5L engines only. The 2.2L is a closed-deck design and has slightly different head gaskets and Subaru coolant is not mandatory for them due to the different materials and design. I should have specified.
As for the system conditioner, they advertise it like it will transform generic coolant into Subaru coolant. While it may add some chemicals and such, it's basically a stop-leak. I can't remember the name, I know it's some sort of silicate, but the Subaru coolant does not have it in and the silicate is supposedly what causes the head gasket failure. This is what is pounded into us by Subaru- "Do not use anything other than Subaru coolant!"