Mystery water leak....help needed!!!

[petesmith]

Hi Guys,

I have a '98 VT Commodore 50th Anniversary V6 Wagon on gas.

I have had a slight water leak for a little while now unknown as to what it is. Since noticing the water leak, I have had the cooling system pressure tested to find no leaks, and the head checked as well to find that it holds 25pounds of pressure (more than the 15 required).
I have recently had the inlet manifold gasket done, bottom radiator hose changed also, this was after the water leak was present. I have had a mechanic check out the heater core with no signs of there being a water leak there. Radiator cap also changed.
When the car is parked, there is no water being dripped onto the ground either. It is probably about 250ml per two days (if not sometimes every day) that I need to top it up with.

It's really starting to do my head in, I don't have any other ideas as to where it could be leaking, or what could be leaking, and the two mechanics that I usually use have almost given up saying that it's a mystery.

Any help would be much appreciated!

[BlackVXGTS]

Do you have any sludge in your rocker covers which would indicate coolant in your oil? Otherwise it could be a head gasket letting water into the combustion chamber(s). Do you see a lot of steam (or even water) coming out of your exhaust pipe? I happened to pass a car that was idling in a driveway the other day and it looked like the exhaust system had been connected to a hose there was so much water coming out of the tail pipe.

[petesmith]

No sludge in rocker cover. No steam out of exhaust, apart from on a cold morning, never water, just steam in the morning but goes away once car heats up.