In the last month or so I have checked the oil level and had to add oil two times. To add to my "confusion" I inadvertently left the oil fill cap off for several miles during the same time period, until I saw the smoke while stopped. Both times I checked the oil after waiting several minutes for it to settle, and both times it was low, so I added a quart each time. Today's instance, after adding the oil I was driving, got on the highway, gave it gas to get in line, and smoked out everybody behind me with a huge amount of white smoke. I pulled over, checked the oil, and it was at least 2 quarts overfull (I think I know the reason for the smoke!). After it sat for a goodly amount of time I drained out the extra oil, started it, and after a bit of smoke it settled down and seems to be working well. My question is why it would show as low oil at times? Did the oil filler being open create some type of "vacuum" or pressure to keep the oil from draining into the pan? I know that I waited long enough to check the oil each time. Also, is there any damage that can occur to the engine (115K miles) by operating with overfilled oil? Thank you.
