Everyone is bang on; on this post.
Only consumable location for oil into coolant to mix are the headgaskets.
Otherwise a crack in the valve-boxes or aluminium block in various points.
Oil pressure > coolant pressure whilst running, I'd expect some mixing to happen when cold/not running, so I would:
Drain the oil if you haven't as lowest point in entire fluid mix.
I'm surprised after 25 years that most people aren't talking about these types of failures because they're all imminent.
I've done 3x engines by now where the composite material fails from improper coolant and maintenance.
Last one was a 147GTA Alfa. Had the sump off to re-seal as was heavily leaking oil. Draining fluid didn't pick up any mixing.
Didn't re-fit right away until next day as had an event that day.
Noticed coolant on the floor next morning in an unusual spot. Pressurized coolant circuit and had coolant pissing straight down one oil return port...
Talk to anyone with a 3.2 Alfa and they will tell you these all tend to fail around the head-studs.
Other one was one of my 3200's that the forum hasn't seen because I haven't had the time to post about it.
I was re-sealing the camboxes and had emptied the entire coolant system(to re-fill fresh).
Last owner mentioned headgaskets have failed, but I wasn't certain until I performed a smoke test on each cylinder @ TDC valves closed.
Had smoke coming out of the coolant manifold at the front of the motor... Game over, everything off.
And first one being my long-time fire-build. They mightn't have failed(yet), but I needed the crank out to spark erode seized waterpump bolts. Full engine rebuild.
If you paid top dollar for the car. Argue hard, especially if through a dealer.
Private sale is extremely tricky because unless written, it's an "As-Is" at time of sale.
If you need parts. I have spare set of OE gaskets on the shelf in SE Melbourne. Not replicas like you might find everywhere else. Not cheap either. But neither is any of the cylinder head work that's recommended before reinstalling(I would not want to ever have to remove them again).
Hope all the best!