At 180,000 miles you are very near the end of that car's lifespan. It's probably just the engine wearing out. The piston rings are worn and they're allowing oil into the combustion chamber. Once the car warms up the metal in the engine expands and the rings are pressed tightly against the cylinder wall no longer allowing oil to seep past (as they are meant to do.)
Keep driving it until it dies. It could last like that for several years or it could die on the drive to work tomorrow.
To the other answerer; even if it is the head, which I don't think it is, the repair would be at least $1,200.00. More than the car is worth.
If you want to make sure it's not the head just check the oil. If the oil level is high and the oil is milky then it's the head, but again, this doesn't sound like a problem with the head to me.