I found the leak! I cleaned up my whole oil pan and found that the drip was coming from the oil level sensor. At least, I believe it is the oil level sensor. It is bolted on to the driver's side of the oil pan, the portion that sticks into the pan is a cylindrical shape. The leak was not coming from the o-ring that seals the aluminum body to the pan though, it was leaking from the small sensor that goes through the aluminum body. I tried to take the sensor out of the aluminum body but it wasn't coming easy and I didn't want to break it. My question is this; is there a way to remove the sensor from the body and get a new seal/sensor or do I have to buy the entire assembly with the sensor already in the aluminum body?
This is on my 87 300SDL with 167k miles.