4 Liters fills it to the Minimum line and 5L fills it to the Max line so that's what I do, Dump in 5L and I'm smack-dab right on.
I would fill to the "Max" line all the time. This is good for a couple of reasons:
1) It gives you added insurance against a sudden leak like a filter or gasket etc. where you might loose some fluid in between checks/changes
2) It gives you extra oil sitting in the sump which makes sure the bottom end never runs dry, even while corning saving you from possible oil starvation.
3) It keeps the general oil storage in the sump cooler because of more volume of oil and allows for better cooling of the engine.
4) You have more additive because you have more oil, and you can hold more combustion by-products and dirt in your oil until the next change due to the extra volume.
More is always better, except when over the "Full/Max" mark on the dipstick, which can lead to engine damage due to aeration.