They're primarily for marine applications, I bought one and used it on my car when I overfilled the engine with oil (compensating for a leak), then fixed the leak.
In hindsight, I guess I could have just pulled the drain plug and collected the fresh oil into something and then poured the proper amount back in but for whatever reason this device seemed easier when I ordered it.
As far as sediment or whatever in the bottom of the oil pan, if you have to worry about that I think you probably need a better filtration device.
If someone wants to buy one for half off, let me know.