Got a bomb *** deal on a 1990 Oldsmobile 88 Royale, Brougham, the 2 door version. She has the pre series 1, LN3 3800 V6. 137k miles.

There is some oil in the coolant reservoir and radiator, as well as a coolant leak, and she overheats. As far as I know, she has overheated twice, each for around 2 minutes. The first time was going off an exit ramp where she was allowed to cool down for an hour, and the second time the previous owner was almost home. I got her towed home then drove around a block to park her.

There are no weird smells, no white smoke, and the engine feels and sounds alright, except maybe a bit rough.

Now, no one wants a head gasket issue which I am worried about, however, the liklihood of that happening with the 3800 is pretty rare, though not impossible.

I'm replacing the intake manifold gaskets, (which were definitely blown) but was wondering if that can cause oil in the coolant from a faulty one? Or if there may be another cause besides the head gaskets?

The lady who had it before me also called the coolant in the radiator oil at one point, so it could be human error. Her dad and her were trying to fix the overheating by replacing all the fuses so...

Just wanted to see you guy'* thoughts about it

Love the foreshadowing.

Oil in coolant, bad.

Is there coolant in the oil?

I'd guess something like this is happening: Coolant leak leads to overheat, clueless driver and clueless dad let it run around overheating over and over and weren't aware . . . because (here'* my foreshadowing) they look at the glove-box latch and the passenger door handle to read speed and temperature. Now many other things are wrong with it.

This combination of factors leads me to believe that you only know of the last two times, they might know of the previous 35 times if the glove box latch was reading properly, and only the car knows of the first 77 times.

Ummm . . . pretty rare unless it has been overheated (77+35+2=114) 114 times.

It is at this point that I suggest you don't arbitrarily start swapping parts. Do a compression test. Do proper troubleshooting. Tearing it down enough to do intake gaskets on the hope that the easy fix is the right fix on a 33-year-old engine that has been to hell and back 114 times probably won't go so well . . . . . . . . .

​​​​​​​ . . . . . . . . because of this.

I'd almost rather know no history of a car than hear this about one.

It sounds like they were going for the easy fix as well. "Maybe the reason the glove box latch is telling us it is overheating is because the glove-box fuse blew! The latch does read a high temperature when we remove the battery, after all." I seriously doubt that they went to the trouble of diagnosing it at all over one overheat. 35 maybe, but not one.

Troubleshoot before replacing parts. My $0.02 .
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Let'* see the oil you have? A picture. After years unless the owner was cleaned them out they will have an oily skum form anywhere the coolant is exposed to air. It'* the oily part of the antifreeze that causes that. We need to verify what it is. The intake can be a problem and may be why it is a bit rough.
Fix that and see what you end up with.