It's quite an easy task, but looks a bit strange on the first look as the Rohloff Oil Change Kit contains a great big syringe! Is this bike maintenance or a medical procedure I'm about to perform on the Rohloff?
The first step is to use the Rohloff Cleaning Oil to help remove the existing oil from the hub. Draw the contents of the blue labelled bottle into the syringe. Then, after removing the small drain plug on the hub, connect the syringe and squirt the contents inside! (Then draw some air back out through the syringe to equalise the pressure).
Refit the drain plug and turn the cranks for a few minutes in gears 3 and 5. (This engages all the hub's planetary gears and ensures the Rohloff Cleaning Oil gets in all the nooks and crannies). Reconnect the syringe and leave with the syringe at the bottom. After 15 minutes draw the old oil out of the hub. Return the contents to the Cleaning Oil bottle for safe disposal.
Fill the syringe with about 15-20ml of clean Rohloff Speedhub Oil. Add this to the hub (then equalise the pressure again) and fit the new drain plug. Job done.
Continue riding, with a near maintenance free transmission system, for a further 5,000 km...