Very interesting indeed. I have also seen a few ounces of oil left in the oil pan after draining via the drain bolt. But with your illustration here AND even an additional the rearward tilt of the car I am amazed.
BTW, I like the idea of using the golf tee to keep the remaining oil in the tube from dripping out.
One concern: I saw that you cut your tube at a 45 degree angle. Wouldn't you get more oil out by reducing that angle? Yes it may "catch/suck" against the pan bottom more easily but a reduced angle would ensure a lower level of oil remaining.
When sucking the oil out the I reach that gurgling sound I usually will lift the tube slightly and reinsert. Seems to get a bit more oil.
As always, thanks for the great pictures and explanations for us DIYers.
'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)