I like to let the oil drain overnight (or all day) or longer. I know there will always be oil left in the motor, but at least that much more is out. My high school friend’s dad had a gas station & he let his car drain all day, said the oil seemed to stay clean longer.
I have now been told that allows the pump to cavitate resulting in dry startup. I disagree, as soon as you take the filter off, air is allowed in the system so the pump will fully drain. I pre fill the filter & “flood clear” to prime the system before starting it anyway.
Is there any fact here? Or just another old mechanic’s tale?