It is a 1993 Cutlass with a 3300, NO water in oil. I thought I'd check and see if this is common and what the cause is . No smoke or oily exhaust pipe. I just dont want to tear into it farther than I have to. Thanks for any help, Mike

Only way I know that oil can get in the coolant without coolant getting in the oil is though the oil or trans coolers built into the radiator itself. Might want to check the trans oil.

OIl pressure is higher than coolant pressure. If the engine is internally leaking, it will push oil into the cooling system. Usually via the head gasket.

Thanks, I didn't think of the tranny cooler. If that isn't it I will pull the intake and heads trying to read the gaskets as I go.

Are you sure? If it is a small coolant leak it may not be detectable in oil unless you let it sit a couple of days then pull the drain plug slowly to see if water comes out first.

Not common on these. They hold up pretty well.

I'd go with what the guys said above ^^^^^^ . A few questions:

How many miles are on it?

Have you owned it and driven it for a while?

Any recent trauma?

How old is the radiator?

In what part of the world does this car live and work?

Can you pick out what color this oil is (in the coolant)?

It has 177000 miles. I saw moisture in the radiator cap a while ago. oil is clean so it'* not my #1 [priority right now.

Like oil moisture?

Oops, I meant oil residue

Okay cool, makes sense because the oil floats to the top and the highest point is the radiator cap on this car.

By the time GM designated the Buick V6s as 3300 and 3800 (a lot of improvements,1989, IIRC), they were very solid engines. The 3300 is shockingly simple and robust for a very modern engine (circa 1989), even though it didn't have the best idle characteristics.
With that said, if there is any oil / coolant mixing on these engines, they have intake manifold gaskets that are nearly as pathetic as the better know issues with intake gaskets on Chevrolet engines (3100, 3400, and V8s). They are a similar plastic carrier and rubber seal around the points. They will slow leaking for a while, just like the Chevy'*, from a little more torque on the intake bolts. Mine weeps oil out the corners. Going to change it soon.
This is the set for a 3300. I don't believe there even any improved designs available.