There was no convenient lower hose to disconnect so I elected to use the radiator drain valve. Just slid a hose onto the nipple, opened the plastic valve, and let it drain.
Filling is fun and super easy with my vacuum filler.
Learning from the past I let it get a -27 in-Hg vacuum which is pretty deep, then open the valve. Once the vacuum equalizes and it has sucked in all it can, I lifted the tool from the tank and inspected the level. It was dead nuts perfect. However I added a bit extra because I have found it can drop a little after running the car. So I have this pretty perfected. I am glad I got that sketchy stuff out of there. I had previously done the intercooler circuit (which is isolated on the S-model).
I need to check the level since it has been sitting all night but it's probably damn close.
If it turns brown again I guess I will change it again but after that things get a little more serious. Hopefully it's fine. Oil in the coolant isn't nearly as bad as coolant in the oil. But, oil in the coolant would seem to support the eventual possibility of coolant in the oil, so it would need to be diagnosed and repaired if I actually confirm that to be the case. Again, hopefully it's fine. There are a number of possibilities with these, though what comes to mind is the oil cooler itself (not the end of the world), or this deadly seal behind the timing cover (which would be a VERY labor intensive job).