Head gasket?

This car has been sitting since January.
I went out and pulled the dipstick, the oil was milky.
In the past when I was driving it at least weekly when not daily there would be some condensation in the oil cap, but never in the oil.
The upper plenum has been replaced around 150,000.
On the engine between the upper plenum and the valve covers there is some oil and or coolant. It's very thin, taste a bit sweet.
The car starts just fine. I let the fuel pump run, then turn it over, and it starts in a "New York Minute". It runs as well as I'd suppose it will.
The engine is a bit "ticky" on start-up, tick in the backside, by the firewall. It doth calm after idling.
A bit of condensation from the tailpipe, very faint white smoke.
I had removed the radiator cap, started the car, let it run awhile. There was no bubbling at all. The antifreeze is clean, however I do have to "make sure" it's full so it doth lose some.
The engine has yet to overheat. It stays at the temperature it has since I bought it in 2020.
Head gasket? Manifold gasket?
Below the thermostat housing, maybe on the thermostat housing, down to the temperature sensor there is noticeable wetness. I've thought of replacing the thermostat gasket.
If this is the head gasket or the manifold gasket I need to prepare to "break it down" I'd guess.