Two days immersion won't hurt too much.
out what you can and get a wee drum of the cheapest engine oil you can find.
Put it in there to the right level.
Start up, and run it for 30 seconds or so. Sample the oil at the dipstick. If it is ok, run it for a bit more, sampling repeatedly. If it looks milky, get the suction pump
out and suck it out.
Repeat, and repeat.
If you are running low on new oil, take the milky oil home and let it stand for a bit. Suck some off the top of the oil and boil it up in a big saucepan until it clears, then suck the clear oil off the top of the pan and dump the dregs. You can use it again if it is clear.
In 1998, I had a Volvo MD17C fail a coolant O-ring and the sump filled with great slugs of seawater. It was horrible, with mustard-coloured oil and it was well above the dipstick max. It was in there for some time before I saw it.
I had to rebuild the top end to fix the leaking liner base O-ring.
About three oil changes cleared the milkiness.
The motor is still running well today, 14 years later.