Leaking antifreeze, looks like its coming from around the serpentine belt more towards the bottom of the engine, might be water pump. is the wate pump down on the bottom of the belt?

Your water pump has a small hole on the top and the bottom of the housing right behind the belt pulley. This is known as a weep hole and is there to let you know when the front seal has gone out of the pump and it is in need of changing. You really want to get this taken care of because on your engine the ignition system is ran off of the crank pulley and is known as "Opti-Spark" when the system gets antifreeze in it it usually goes bad. The Opti-Spark distributor sits right underneath the water pump, so a leaking water pump soon will take out your distributor which is another added expense.

If its driven by the serpentine belt you can use a breaker bar to see if you got some play on the poulie of the water pump and check for leak if its driven by the timing belt not mush to do except look for a coolant leak ill give you a video example you didnt say wich model you had

3.3 AND3.8 ENGINES TAKE OFF SERPENTINE BELT 15MM ON BELT TENSIONER . REMOVE 2 HOSES OFF PUMP. 5 ?BOLTS AROUND WATER PUMP. IT WILL COME OFF WITH ANTIFREEZE LEAKING OUT. HAVE DRAIN PAN UNDER . ALSO IT IS GOOD TIME TO CHANGE THE LOWER HOSES. REINSTALL WITH NEW GASKET, FILL SYSTEM, PUT HEAT ON HOT AND RUN UNTIL THERMOSTATE OPENS, AND CHECK FOR LEAKS, TORQUE IF NESSESARY ( ENGINE OFF)!!REFILL AT SIDE TANK

Check the seap hole at the bottom of the water pump for a leak. If that's where the leak is coming from the water pump will need to be replaced. Otherwise check all hoses and fittings for a leak.

Sounds like the radiator is OK...if you cannot see any visible leaks...if you have inspected upper and lower radiator hoses and connections...it could be the water pump...however you should be able to see some antifreeze around the water pump pulley...changing the water pump on your Oldsmobile is not a major job...you do not have to remove any motor mounts to do this...only if your serpentine belt is worn and needs replacement...your Olds will require the removal of the upper motor mount in order to change the serpentine belt...sounds like you are on the right track...:)

DO NOT RUN THE CAR WITH NO WATER,water has to be present in the reservoir to enable the output of heat from the heaters. switch the engine off put water in the reservoir/antifreeze look at the bottom of your engine, see if there is a leak, ifnot fill water on to correct level, close cap, turn engine on, check for leak under the engine, if not when engine reaches optimum temperature, your car should give out heat. after an hour check level of water in reservoir. if it has totally depleted or decreased by a significant amount then, go straight to the mechanic and tell him your observations, it could be your HEAD GASKET, if it is then start saving

could be the water pump, have it checked ASAP, you do not want to overheat the engine.

Most likely a leaky gasket. The water pump is a likely candidate, but also could be from a bad radiator hose/thermostat connection. Would suggest washing down the engine with a hose connected to the hot water. While the engine is cold use the hose to wash off the oil & grease deposits and old antifreeze. Allow the engine to dry without running the car. Once dry start the car and be prepared to look for the first sign of a leak. Sounds like a dealer issue since there is very little work clearence between the front of the engine and the car body. Barely enough room to be able to change the serpentine belt.

Probably a water pump seal unfortunately. Pressurize the system, with the engine off, use a mirror to look under the water pump pulley to see if any fluid is dripping from the water pump seal weep hole.
If it is, change the water pump.
Good luck, let me know.
Regards,