[Jay11STI]

Yeah the coolant level in the overflow tank is annoying since it will always be changing. Since it's not a fully closed system, the coolant level can and will vary depending on the outside temperature believe it or not. Coolant level in the winter will be different than coolant level in the summer. For example, starting off with it at the low mark in the cold winter may actually turn into starting off in the middle in the spring/summer. Get what im saying?

Personally, I think its best to check the bottle on a completely cold engine after it has sat overnight. Like first thing in the morning before the first start up. You need to make sure you are also checking it on level ground and or in the same spot every time. On my own car, I prefer to just keep the coolant level in the overflow bottle somewhere in the middle.

I would also make sure you have good rad caps on the car. If they haven't been replaced in a couple of years then by all means replace them with brand new subaru oem caps. Those caps play an important role in subaru cooling system and one of the things they do is control how much coolant goes into the overflow bottle.