I am kind of like Curly, think folks change oil pretty often when they may not need to.
My truck and tractor guys used to leave in if forever and until I got them to use STP or Lucas, the iron parts in the motor would rust up. Never any damage from leaving it in a bit longer that I could see.
If the oil has the milky look to it, get the temp up for a bit and cook the moisture out of it while it in the motor!!
Take care, K