I did the drain pan thing for years, until the plastic drain pan began to leak -- a steady stream of oil. Thank the gods it did that before I put it in my trunk to take it to recycling!
And for those of us who have no place to put ramps or to deploy them, and/or with cars that have belly pans, an oil extractor is a fantastic thing. In theory, if your car has a filter you can reach from on top like my Mercedes, you could drain your car's oil without changing out of good clothes.
My Topsider got 5.5 quarts out of my C230's crankcase, which was supposed to hold 6. I didn't do extended drains, so I think there was very little left in the engine at each change that could cause any troubles.
As far as my 420SEL, a V-8 w/ 8 quarts in it: I did Topsider changes on it for two years. A few months before the car was totalled, I had to have the oil pan replaced -- it had been dented by something in one of these cart tracks New Orleans pretends are roads, and was leaking. My regular mechanic said the old pan, and the inside of the engine (with almost 200K on it), were as clean as the proverbial whistle.
I only wish I could extract the oil from my Buick and change the filter from on top!
