It's time to flush the transmission oil. I found instructions here, but can't get past the first step. ("Using two wrenches, ... remove this cooler line.")
https://www.volvoclub.org.uk/faq/Tra...X940FluidFlush

I've dribbled penetrating oil onto it for a week, but it won't budge. It won't turn. It won't even creak. (it does seem a little loose in the radiator grommet ... does it mount in the radiator the same was as the grommet the radiator-fan switch is mounted in?) I suspect I'm holding and turning the wrong things.
Does anybody know how to remove this fitting? What kind of fitting is it? Does anybody have a photograph/illustration of this fitting after disassembly & removal?
I'd hate to resort to cutting the line and mending it later with a Swagelok union, but I'll do what I have to do.

 

You hold the big nut, turn the smaller fitting to the left. The big one is inserted into the plastic radiator, therefore you have to hold it as it doesn't seem like it'll reseal after--radiators come with that already installed.

You may want to remove the sensor above to get a better position for the wrench.

 

Rereading your post, that big fitting should not be turning; I am not sure how it attaches but it's not supposed to be loose or removed.
The temp sensor above is pressure fitted, just stuck in there into a rubber grommet which sometimes just blows out! I always zip tie it to keep that from happening (that's for later obviously).

 

Just as depicted in the bottom photograph?

 

yes. that's correct, you hold the big fitting, turn the small

 

That's not encouraging. I was hoping I was missing something and there was a top-secret inside-information technique available.
I'll keep at it for a while, in hopes of breaking something loose, and probably succumb to installing a union. I'm not hopeful -- it's probably a compression fitting, assembled dry, and the two halves have been tightly screwed together since 1993.

Now I'm worried what I'll do if/when the radiator needs replacing.

Thanks for the straightforward info anyway.

 

Soak it in some good penetrating oil for a couple of days, it should come loose!

 

could also try spraying the bigger fitting on the radiator side with some freeze mist (duster-in-a-can) to get it as cold as practical, then apply a little heat (propane torch) just to the smaller nut, THEN try and bust it off. don't overheat it! you want the inside cold and the outside warm.

 

After dribbling penetrating oil onto it for a month or two, it finally worked loose.
Inside, it's an ordinary flare fitting. It now has PTFE tape on the threads.

 

a flare fitting shouldn't need any tape or other sealant.

 

It's on the threads, not on the sealing surfaces, to increase the probability of it unscrewing easily next time.