I changed the oil on my 1989 BMW 325is about a week ago and noticed A LOT of bubbles uniformly spread on the dipstick (essentially foam)immediately afterward. I did NOT overfill the crankcase. The engine was still warm at this point. However, when I drove the car around for a couple of miles, the bubbles decreased noticeably, but were still there. When I checked the dipstick the next morning, there were no bubbles and everything looked dandy. Today I decided to take another look after a few days after several miles of driving (engine still hot), and noticed some bubbles still present. It's not nearly as bad as it was last week, but it bothers me somewhat. I've never had this problem before. I read that the two main reasons for bubbles are overfilled oil and coolant leaking into the oil. Since I changed the oil myself, I know that I didn't overfill. It's also not high on the dipstick. However, I don't know how to reliably check for coolant in the oil. Any help? thanks.