DIY Oil Change Observations (2 Viewers)

[Bret_T]

Make sure to open the drain plug and then remove the filter. If you put the drain plug back in before you remove the filter, there is no sump and a considerable amount of oil will remain. I probably got another 1/2Q out when both removed (all 3 actually-as well as the oil cap filler under the hood, obviously).

Would you please elaborate on this as I'm not following the logic behind it? Where would the extra oil remain? Why wouldn't it just gravity feed out of the oil pan plug hole or the oil filter location to begin with?