Originally Posted by Musikmann
I have been seeing recent posts that it is better to drain your oil the old-fashioned way. The reasoning is that the oil pumps miss some of the sludgy crud that might be hiding in the bottom of the system. That said, good luck in your quest.
I have only seen forum members who are strongly against oil siphoning and forum members who see no gain in draining. Perhaps it is just that neutral opinions are not posted.
Would be nice if someone had access to a typical MB oil pan that has been designed for oil siphoning and would take a photo. Well, I could take a photo from outside of the pan but it needs some work to remove the panels. An inside photo might be more convincing.
On an older MB I've tried to siphon the oil first and then drain from the plug, and did not get anything from the plug. I know some members claim the opposite. My claim is that the oil pan is designed for siphoning and the dipstick tube reaches the lowest point of the oil pan. The drain plug may does not have to be even as low although of course nothing much of oil would be left after draining.
Now if there is some "sludgy crud", I don't see a difference with the two methods because the oil flow is equally strong for both, if you use a proper siphoning device, the oil comes really quick with a large top connected siphoning tube. On the other hand, sounds dangerous for the car if there could be any of that crud that still moves in the pan, at exceptional car tilt, the stuff might block the oil pump input.
Car levelling is of course important in all cases. Draining might have an advantage if they had a magnet at the drain plug but I've understood it does not exist any more in modern cars.
I'm not trying to talk people to use the siphoning method but more to make everybody think about it and make their own decision instead of picking up one or the other view they may hear from one person.
Edit: one more comment, I had a look at WIS and it seems to be the first "neutral view", WIS explains both methods equally.