I recently brought a trade in to Boch Chevrolet in Norwood, MA. I accompanied the sales manager as he evaluated the trade in. He immediately went to the right front tire and identified a liquid as oil on the outer wall of the tire. He suggested there was an oil leak, which would impact the trade in value of the car. I questioned the source of oil. Given the location and pattern of the oil, it was apparent that the car was stationary when the oil was applied, and that there are no mechanical structures that would drip oil on the outer wall of a tire. The oil was exceptionally clean, uncharacteristic of oil leaking from a 12 year old car. Of course, the sales manager was not eager to offer an explanation and offered none when asked. To the best of my knowledge, tires do not leak oil!
We brought the car home and have been driving it for several weeks. Quite mysteriously, there has been no sign of oil on the right front tire! No other sales managers found evidence of an oil leak during their assessment of the car. This seems to be a phenomenon that occurs only in the parking area of Boch Chevrolet!
Having been a service advisor for a reputable car dealership, I am well aware that there was and is no oil leak.