The car needs to be level or it won't drain properly.
I raise the car on the jack, pull the plug, and then lower the car back on the wheels for 30 min. Then raise it, swap the filter, button it up and lower it again.
I also use a polycarb buspan for my drain pan - available at any restaurant supply for about $5. It low enough to allow lowering the car. I also added 0.5 qt. index marks on the side using pre-measured amounts of water and a sharpie, so I can measure how much came out. Then I know I got it all and replacing that amount, won't overfill it.
If that's too much hassle, just refill with 8 qts. and top it off over the next few days.
