On a gauge its not seen until 1 or 2 seconds of it occurs because the psi behind the sender is still somewhat constant with oil timing closing the door behind till the next window relieves enough psi.
Heres something for people to chew on...there is probably about 2 -2 1/2 quarts of oil in the factory 5qt pan, maybe, while running up above 5500 rpm....the rest is in path or suspended/falling out/draining back.
