Take a good look at the standpipe in the filter housing the next time you change the filter. I think you'll find that there's a 1/16" hole in the standpipe about at the level of the inlet port in the side of the canister. That's as far as the filter will drain, regardless of the fact the drain hose is at the bottom of the housing. After the engine sits for an hour or more, the dipstick level will rise about 1/2 quart or so as the filter drains halfway.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!