It really doesn't make any sense for the filter body to drain when the engine is shut off because:
A. It has to fill up again when you start the engine which will give you low oil pressure just when you really need good oil pressure.
B. You will have a dipstik oil level problem where the stick will read a quart high.
This doesn't mean you aren't correct about your instructions for the filter you reference, but I bet the the oil won't drain back into the engine either when it's shut off.
Seems like the oil actually comes up the center tube, so the level won't drop below the top of the tube or the side outlet.
It's been way too long since I got into this, but I seem to remember changing the oil for the first time on my '53 chevy, and trying to drain the oil out the bottom, which didn't work, and finally unbolting the filter and dumping it out.
This was when I was a dumb and stupid 16 year old, and before I learned about the joys of a turkey baster.
Kurt
