Key words here..( in my opinion) are "used to run into the air box" and "capped up"
Did you cap it? How do you know it "used to" run into the air box? and why was it capped?
Milky white is water condensation and oil, usually. When you uncapped it did it run down the battery?
Please step back an post a picture of where the hose originates.... that will give us a better idea of what it is and where it should go.
One other thing.... how long was it sitting and in what humidity and temperature? sounds like it was stored outside in the shade (or covered) and was put out in the sun for a few, (then started or an attempted start).... or a garage that was not heated for the winter.
If you ran it for 15 to your house, you should be good to go if you change that oil....
If after the oil change it still drains that color.... you should check your casing bolts for tight.... might be that water is getting in the case through the split line, but if its not leaking oil, i'm not sure where else.