When I did my brief flush, I had both the sump plug and oil filter off at the time.. just to eke out every last drop of the black stuff .. probably 3 hrs or more draining, went to the market with my dad and all that jazz.
Can't remember but I think I even lifted the front of the car a bit too and a few hundred mls exited the plug too.
My other problem is that I can't get the sump off without a chisel either(tried).
Someone has sealed it up with some cement like goop.
Doesn't leak, that's for sure, and I don't want to risk damaging the block face.
Tried to use a screwdriver on the goop(between sump and block) and all it started to do was bend the sump down without releasing it at all! Tapped it back with a small hammer and put all the bolts back in and left it.

