if i think i have a head gasket problem how long can the car be drivin as is ?

Cover the ground underneath the front of the car where you park it at night with something that will show wet spots. This should help you identify whether there are external leaks (hoses, radiator, water pump, thermostat housing). And I am assuming you are not seeing any coolant leak from the heater core inside the cabin. If you have a head gasket failure, your exhaust will be "white smoke" (steam, actually) immediately when you start up a cold engine. That's water that's accumulated in the combustion chamber while the car was sitting still, which is turned into steam. It's hard to predict how long you can drive with a head gasket failure -- weeks or months. It will, however, get worse and not necessarily in a steady fashion, but potentially abruptly. If you get a lot of coolant into the engine, you could experience "water lock" when the valves close and the cylinder is on the compression cycle if there is not any air left in the cylinder. This will cause significant engine damage and result in a much more expensive repair, up to and including a new engine, than simply replacing the head gasket.

did you ever figure anything out about this? i think mine might be doing the same thing.

ok 1 it may not be head gasket theres cps reasons a saab uses coolant. 1 air in line or clog in hose in which case will cause it to use more coolant on start up 2 could be a pin hole in a hose in which case you won't see signs of leaking or 3 it cld be your heater core which you have to take passenger side dash out to get to that one