Have owned a 1977 R172K with a Continental IO-360k for a little over a year. Consistently noted a lot of oil on the belly and excessive draining from the overflow tube after each flight. I thought i was doing the right thing keeping the oil level in the middle between the 6qt and 8qt marking on the factory dipstick. Recently helped the AP do an oil change for me and after 6 qts we couldn’t get a reading on the disptick anywhere close to the 6qt line. Same for 7qts. With 8qts it showed under the 6qt line but somewhat close. Pic attached. I called Continental Motors and they were were very helpful, explained they had a service bulletin about the issue, and arrange for the dipstick it to be replaced as warranty claim.