bart,
im no master mechanic by any means, but when you are filling up the resevour, are you sure that the radiator is full also?? otherwise, if the rad is low, and the resivor is full, when the engine warms up, it would drop the level in the res. dramaticly, and make you think you are loosing alot. also, when the engine is upp and warm, have you done any sqeezing on the hoses??? SOMETIMES, when you sqeeze the hoses and everything is under pressure,you can cause the leak to actually "squirt, or spray" instead of just drip, and be hard to find. so get your flashlight, or 1000 million candlepoweer spotlight, and start looking between the radiator fin while your squeesing the hose, look at seams while squeezing, and so on and so on. anywhere there is a hose, or connection, the drain nut tranny lines, etc. any leak can be deceptive from it leaking, and the air blowing that leak allover the place makes it harder to pinpoint. dont know, just trying to help. maybe this is obviouse stuff. good luck with it.......im pullin for ya
david