Regarding the leak noted in the photo: Looks like a typical pushrod seal leak, not catastrophic but does require attention. Fairly common leak and requiring a common “in field” repair.
I wouldn’t put to much value in the photo because we don’t know the history e.g. was this on the last leg before the photo was taken, was it between a number of stops where repair wasn’t possible, etc. We simply can’t tell over what period of time the photo records.
Finally, keep in mind that a teaspoon of oil from one of these radials can look like you’ve lost a full tank! Been there done that!
Ted Campbell