3.7 liters, or until full! I use Rotel 5W40.
Sorry mate, it'll work out to be too much.
I know the manual states 3.7 litres.
But it's wrong.
She won't take 3.7 litres. Even if one purges all the contents out of the scavenging pump, with filter change(naturally) and left to drain for a long time from a hot engine.
If you put 3.7 litres into it, it will in fact be "quite a good deal over full" when one checks it when the bike is cold and level.
This will strongly motivate one to remove some oil(fact). Or one will be on the forums complaining of putting exactly 3.7 litres in and it's over full. The next question will inevitably be "what's the easiest way to remove the excess oil".
And it's not easy or convenient and it's a bit messy.
3.7 litres of oil will end up putting the level at (some where ?) over the top of the sight glass, when checked dead cold and with bike level after a run to get the oil nice and hot.
My hot tip for a service refill capacity on the 1199, is to only put (3.5 litres) in as a starting point.
Then recheck it after a run to get the oil hot and the bike has completely cooled down(nearly or completely cold and with bike level).
If one chooses (not) to purge the scavenging pump then about 3.45 litres will be suitable as a starting point for the service refill capacity (I think the pump holds about 70 ml).
So in summary, It's better to be close to having to add a little oil, than to be quite over full from the start.
I have repeatedly found on the 1199, that using 3.5 litres as a service refill capacity will get one to within about 50 - 70 ml off the top mark on the crankcase, with purging the scavenging pump and filter change.
Then later on, one may add a little oil as required to suit when cold and level.
Good Luck