[edit: figures intended for old 650 only
]
Um, basic stuff here, let the stuff drain out
You will notice, whether you have a center stand or side stand, the bike leans one way or the other. If you can tilt it forward or backward so that most of the oil comes out all the better
Once the filter is off, there will be yet more old oil, let it drain. Time is the issue, if you have some, let it drain. If the oil is warm, it will take less time(and incidentally remove more gungy bits than cold oil)
Once you are satisfied you can screw in the drain plug and install the new filter and fill with oil.
At this point I have to say there is no need to muck around with leveling the bike or which way it leans, you have two choices:
1. You were a good person to your bike and changed the oil filter - add 2700ml oil, that's it job done go ride ***Seriously, bugger all this leveling and sight glasses and topping up, if the engine is empty, add 2700ml, job done
{the best part here is I have a 250ml oil resovoir for my chain oiler, every oil change I add the extra 300ml out of 3lt to my or as much as I can and I am good for another 8,000km)
2. You were less than ordinary to your personal transport and did not change the oil filter, add 2400ml oil(double check this figure, I have never done it so am not 100% positive), go for a ride
keep in mind, there was old oil in the filter, it will dilute your nice new stuff, Suzuki say change every two, the choice is yours, filters are cheap, engines aren't.
No real need for a new sump plug crush washer, but if you have one use it if you wish
Tighten the oil drain plug with the OEM spanner, unless you are Arnie your strength and leverage should make the nut tight not strip it.
that's it, takes about 20 minutes, allowing for drainage, buying oil and filter etc, then go ride.
Cheers
TS