That's funny.
No disrespect intended. I guess there might be someone who would reuse old oil.
You put a smile on my face.
The measurement of oil is indicative of how much did not drain out. Or, how much contaminated oil remained in the system. 1/3 of system capacity did not drain. That does not seem like a good thing. I do not think that is as designed.
The filter was fairly new with not many hours. I did not change it. I will change it with the next oil change. Base on the hours vs time; I guess it will be 5 hours or no more than 1 year which ever comes first. This is one of three tractor and it rarely gets used. At close to $200 to change all the oils and filters, it gets to be very expensive to justify at only 5 hours a year. It is still cheaper and more convenient than renting.