Why do struts leak?

[svx_commuter]

This is a picture of the front right strut with the various parts shown. The top of the strut has been removed to get the parts out.
http://www.subaru-svx.net/photos/fil...muter/5662.JPG

Let me know if this what most other insides look like. In this arrangement when it's all together, the top guide and lip seal mate up metal to metal with the plastic baffle in between them.

During the extension stroke as the fuild moves up it would pass thru the upper bushing guide and past the the baffle. the baffle has slots to let the fluid pass. The ID of the baffle is a lip seal too. So that makes 4 sealing surfaces on the shaft. The slots in the baffle and top guide allow the fluid to fall freely back into the space between the working cylinder and the outside cylinder of the shock. At least that is what I see.