My fettle today was an oil change on my Rohloff hub ebike.
I've done a Shimano Alfine hub before, but Herr Rohloff makes things a bit more complicated because you need to put flushing oil in, ride the bike, suck out the oil, then refill with oil from a different plastic pot.
Removing and refitting the drain plug was easy enough, which is just as well since I had to do it several times.
Unlike Shimano, there's no O-ring to perish, I suspect the plug may be slightly tapered.
it's certainly easier to start the thread than on the Shimano, a dab of bike grease held the plug nicely on the end of my allen key.
Strict instructions from the Germans not to overtighten it, the plug needs to stand a bit proud of the hub casing.
The flushed oil I sucked out was suitably gunky, and was about the same volume as I put in.
That's as it should be, the Rohloff is designed to sweat oil over time, and the instructions say it will work fine with no liquid oil inside.
In other words, the oil coats the internals so there isn't meant to be a sump of it sloshing around at the bottom of the casing.
There's also stuff in the instructions about air pressure, and sucking some air out after the final fill.
I did draw the syringe back a bit, but there are limits - the pressure will sort itself out over time even if it hasn't already.
Rohloff specify annual/5,000km oil changes.
I think the first change is worth doing, but I won't worry if I go a bit over time/mileage next time.
As a fellow Rohloff owner,
@Littgull may be interested in this post, although I know he's more interested in riding bikes than fettling them.