3.0 L is perfect. Do not add more or you will over fill. It'll read a bit low until the bike gets fully warmed up. And I don't mean letting it just sit and idle. I mean after you've put 3.0 L in and go for a decent ride, preferably at highway speeds. Come back and check the dip stick and it'll be right on the full mark.
Re: oil change taking so long. It doesn't. I just did my first oil change on my 990 a week ago or so. It took 45 minutes. You don't need to remove the gas tank. Heck, I even checked and swapped out the oil reservoir screen without the tank removed.
Firstly, remove dip stick from oil reservoir, drop the skid plate, pull the engine drain plug to drain off engine oil, swap oil filter, swap or clean oil screen.
While the engine is draining off I move to the oil reservoir. You can get at the oil reservoir drain plug without removing the tank. In order to drain off the reservoir's oil without getting it all over the place, just use a small funnel, and tuck it in there under the drain hole. I prefer the Flo Tool 'Tight Spot' rubber funnel:
If you put a length of clear hose on the end of the funnel it makes it even easier. I let that drain off.
Now I remove the bottom fuel tank bolt from the side where the reservoir drain plug is. Don't remove the top two. This allows the tank to swing out on the bottom a bit, giving you easier access to the oil reservoir screen. Using a long extension ratchet you can get at the two bolts for the reservoir oil screen. Clean or swap. Reinstall.
Now button everything up. Reinstall both oil drain plugs with new washers. Make sure to reinstall oil filter lid and oil screen lid. Be sure to use a torque wrench and follow torque guidelines. The 'good n' tight' method will get you into trouble quick, as humans typically overshoot proper torque by ~5 Nm when we do it by 'feel'.
Now pour 2.5 L of fresh oil in the reservoir. Put the dipstick in. Run the engine until 6 bars on the temp gauge show up. Then shut the bike off and pour the remaining .5 L in the reservoir.
You're good to go.
I suspect the next time I do it it'll take 30 min.