I got a letter from Subaru about "a special conditioner be added to the engine cooling system of certain 1999 to 2002 model ... to prevent a possible external coolant leak in engine cylinder head gaskets."
I searched google, but I still don't have an idea about how bad this is. My questions are
1) Do I definitely have to do it? How bad it is?
2) I just did my 90K maintenance at a non-dealer shop. In the future when I flush the coolant, do I have to go back to dealer to add this stupid conditioner?
Thanks very much for your help.