Lude Generation

The coolant level in my radiator is dropping, over a period of 2 weeks or so, but the level in the overflow tank, does not move. I have checked for leaks under various operating ranges, i.e engine hot, and running, engine hot and not running, and engine stone cold. I cannot see any evidence of leaks. Any ideas guys?
Cheers.
Tony.

Heater matrix?

Well, i have not noticed any wet carpets, but i will check this more thoroughly. I thought coolant should be drawn from the expansion tank, to keep the radiator constant? My expansion tank stays on full the whole time!!

i had the same issue - leak was traced to the two small rubber coolant hoses that feed the oil cooler at the back of the block. reason i couldnt spot it was the coolant was dropping onto the hot manifold and evaporating so there were no tell tale signs of coolant loss. One of the hoses was split just at the edge of the hose clip and you could only see it when the car was up to temp and under load

might not be this but definately worth checking