Coupla facts:
1. The Rohloff's breather hold is in the axle hollow. Where there's a hole, oil will seep.
2. There is no way that you can remove the correct amount of oil, about 12ml, from the Rohloff gearbox. It isn't so much liquid as a film sitting on the gears. So, no matter how much drips out, no harm will be done.
3. The standard 25ml is 66% more oil than the 15ml actually required.
I were you, I'd do nothing and wait to see if the oil stops dripping. I had a dripping problem that started some months after an oil change, at the change of the season, so that perhaps there was a change of general ambient air pressure, and I did nothing, just waited it out. At the next, routine oils change, done at the normal time, I got less than expected out with the cleaning oil, but no harm appeared to have been done. On an earlier occasion, with a smaller drip,on advice here I changed the oil out of turn, but what came out appeared to be absolutely clean, so it was a waste of a service kit. Worth it at the time for the peace of mind though, so there is something to be said for it if you are well off enough not to count the cost of a service kit. But the longer I have a Rohloff, the less I worry about ta little mist of oil that seems to hang around it occasionally.
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Jobst Brandt, a most distinguished engineer (he designed the first Formula One disc brakes, for instance) and and even more distinguished cyclist (multiple Alpine crossings when he was already older than some of us would be lucky to get to be) always insisted that any seal that isn't leaking a little, is in the process of drying out and wrecking itself. A seal works by passing a little oil to lubircate itself and seal itself to the wall of the aperture. Makes sense. (I'm paraphrasing Jobst from memory. I hope he isn't getting apoplexy when he reads my version of what he said!)
Andre Jute
