Saturn sc1, oil leaking into antifreeze

..wwwoooaaa.... sounds like you have either: a cracked head, a cracked block, a leaking head gasket, leaking intake gasket,..your antifreeze should NOT mix with anything...

.UNLESS YOU POURED THE ANTIFREEZE INTO THE OIL FILL NECK!!!

Clogged radiator, worn out water pump fins, oil pump failing, head gasket blown and leaking into the cylinders, thermostat stuck closed.

Water pump bearing. This will cause coolant loss and rapid belt wear. Replace the water pump along with a new belt. Check idler pulleys too while belt is off.

Your water pump went out. The sound was the bairings in side the water pump. The leak is from the seal also going out on the pump and it will leak all the fluid out. Replace the water pump.

you need to find that leak, is the leak visible? if its not from radiator or the reservoir, the only other place I could think you can lose water is the head gasket. It happens to high miles and hard driver. 100k miles would likely be a head gasket. Leaking head gasket will also cause the engine temperature to rise and run super hot. antifreeze will leak through the head gasket down to your oil pan mixing oil and water. Check your oil by pulling the dip stick and see if you have oil mix with water; it will have a slimy looking colors, oil is light color and it should never be black. if it black than change your oil and inspect it afterward when the car has been running for while. when engine really hot cause the heat to effect the starter not to engage or start or engine is too hot to run. repairing head gasket could run anywere from 500-800 bucks.

the oil is almost certainly being burned in the engine, this means the piston rings have lost there seal, u will need an overhaul of the engine.

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

my be the front pump seal is no good it leaks when it seats

The water pump is on the front of the engine. Does it look like a hose leak?

could quite possibly be the water pump. There is a weep hole under the shaft, when the bearings go, the antifreeze leaks out at that point. Try checking w/ motor off using a small mirror to get a look under the water pump. If u see corrosion, or it's wet, get a new pump installed. Let me know what u find. good luck countrycurt0