[big911fan]

I've been thinking about replacing the water pump on my 2006 Boxster S as a preventative measure. I only have 27K miles on the car but I understand age can take it's toll on the composite pump vanes.

My question is this:

If I replace the water pump and thermostat/housing, how much coolant should I expect to lose?

The capacity of the system is 6 gals. but will I lose all of it, most of it, or just a small amount of it during the replacement procedure.

I want to be prepared with the correct amount of new coolant on hand.