your rad has a hole in it or u have a brokin rad line
Check the water pump. Examine it for traces of dried coolant that might be leaking out of the casting.
The Commodore requires a gycol based coolant, its uses a50% coolant, 50% water mix. Ensure the coolant you choose is a high quality and suitable for V6 motor
Worse case could be from a rusted out welsh plug on the rear of the motor. Also could be a heater hose or a intake manifold gasket leaking on the end. if so the valley will need removing.
coolant, motor oil, power steering fluid, transmission fluid, brake fluid?
No, you run the risk of destroying the motor.
It is possible for coolant to leak out between the motor and transmission, if a freeze plug has been leaking. I had this problem on an old International Travelall I had. The motor will need to be pulled.
Rear main engine seal or front transmission seals
The thermostat is under the housing that is attached to the top radiator hose on the front of the motor.
There should be a seep hole in the front of the pump either under or behind the pulley. Usually if the pump is done, there will be coolant leaking from there. If you are rebuilding the motor, it is cheap insurance just to replace the pump.
If coolant is leaking from the back of the engine it is most likely that the intake gaskets need replacement or a possible heater hose connection depending on the year.
it is probably your water pump
Either a blown head gasket or a cracked block possibly