If I were you, I'd chance it, especially if the Rohloff HGB was properly serviced before being put up in the garage, and especially if it isn't near-new and still knocking microslivers off the gear-teeth, and service it fully at the first opportunity. At your own risk, of course.
***
If the bike really needs the service immediately but you burn to ride, and if you have the cleaning oil and the four seasons oil and the syringe but not the tube, you can cobble up a temporary substitute from common things found in the house. I found all of this in the photo in my study, without even going up to my studio or down to the kitchen.
Not shown: If you can find a small funnel in the kitchen or the garage with a thin tip, you're set.
Not shown: my treadmill came with a bottle of oil with a spout. Ironically, I now use a spare Rohloff syringe and tube to service the treadbed, and have long repurposed the original bottle and spout to something in my studio.
On the photo, from the left:
Earbulb -- for washing wax out of ears; this one had a fine tip that will fit the Rohloff but I cut it off to fit the fountain pens I force-clean with it. I have another one that came in a watchmaker's kit to blow dust off watch assemblies.
Fountain pen cartridge adapter -- it's even got a screw for forcing the oil into the Rohloff.
Fountain pen cartridge -- cut one end off, squeeze to load and discharge.
Eyedropper -- came with a bottle of something for my wife's cats.
Pipette -- for measuring all kinds of things in small amounts but actually holds 5ml and the tip is small enough to work and you could probably cut it a bit shorter to get a tighter fit.
Water brush, comes in all sizes -- unscrew the barrel, squeeze to load the oil, pull the brush out of the end (these things are cheap) and you have a stubby little tube that will fit the Rohloff.
Needle for people size syringe -- not required if the syringe end fits, see next item --
PLUS
People size syringe -- I begged used ones at my doctor for measuring and injecting tiny amounts of stuff into artist's paints, and was given a double handful in sterile wrappings. If you have a dog or your wife keeps cats, there may be a veterinary syringe lying around somewhere (the Rohloff one is a horse size vet's syringe, only the tube is special).
Needlenose squeeze bottle -- pull the needle out and you have a little spout that will fit the Rohloff and a squeeze bottle behind it.
Another squeeze bottle, smaller but you don't need to pull anything out to pass a useful amount of oil.
Not shown: If all else fails, get a plastic bag from the kitchen, make a much smaller hole than you think you will require in one
corner, feed the corner into the Rohloff oil hole and tape that end of the bag securely to the hub, then slowly, slowly, slowly, feed the oil from the syringe into the bag. Probably messy but when all else fails...
