I'm not sure what I'm giggling about more, the poor woman who didn't do what she should have or the possible misdiagnosis by your shop.
Oil in the coolant due to LIM'*. The only way this is happening is if the leak is bad and the car is cooling, drawing oil into the coolant. The part you are missing is that the coolant would clearly have pushed into the oil and destroyed the motor by now.
Does the oil have a reddish tinge? I assume it does. I'd go check the level of the trans fluid if it is reddish.
Diagnosing motor leaks if commonly a matter of deciphering pressure locations.
LIM Gasket: Coolant would have a better chance to get into oil at the LIM gasket based on the coolant being 16psi and the oil being drip return (0psi) at the intake gasket.
Radiator: Trans fluid of Xpsi (over 16psi for sure) flows through the trans cooler which is in the endcap of the radiator. Trans oil can get into the coolant in this location.
Coolant in the cylinder: ***MOST MOTORS, NOT 3800*** Typically a head gasket, the vacuum of the motor combined with coolant pressure will draw coolant in during an intake stroke and push exhaust bubbles into the coolant during the compression/exhaust strokes. 3800 this usually means a bad UIM (if NA) or a bad supercharge/TB gasket. Headgaskets are extremely uncommon on the 3800.
I'm not beating your down or trying to belittle you at all. Just help out by posting some info because there is some bad information about checking oil if the LIM gaskets go bad. When your LIM gaskets go bad, they push coolant intot he cylinder. Pretty well sealed area. It doesn't dump into the oil in quantities that would make it milky or foam up.
00 Regal GS: All kinds of cool stuff.