[jakeru]

I've topped off my coolant tank a couple times since I've picked up my 2001 Boxster base, a couple years ago. Previous owner I think provided receipt of the expansion tank being replaced right before I got the car, along with a new OE "Blau" brand (but not genuine Porsche) cap. Ive noticed no evidence of leaking or evaporated coolant crust down below. Since the cooling system is such a big capacity, and may be difficult to get all the air bubbles out, I figured perhaps it may just be necessary to top off very infrequently. I can't really say the coolant level has completely stabilized, however. I try to not remove the cap more than is necessary. Never had any performance problem with the cooling system. Not sure if this helps, but for what it's worth...