The manual says the difference between the dipstick maximum an minimum marks is 700 cubic centimeters, which converts to approximately 24 U.S. fluid ounces. However, when I add oil this doesn't seem accurate. Today the oil level was exactly at the minimum, and I added 14 oz of oil, which brought the level nearly to the maximum mark, indicating the actual differential to be 16 oz. This has happened several times. I'm stumped. Any ideas/experience with this issue?