dont know what brands you have over there in sweden, hypoid 80 or 90, drain the dif on the main stand then top up on the kickstand,130ml approx,it wont take that much oil, taking the right saddlebag off is your best option, or you can struggle with it inplace, ive done it both ways on the 1200, most ltr bottles have a pouring tube
As for what kind of oil I like the slick kind. That works the best.
To fill the final drive the very best tool you can use is a simple oil can with one of those flexible arms and spouts. No need to hassle with a hose on the end of a bottle that likes to pop off and spill oil all over the place, no need for a pump like for a outboard lower drive, one of the oil cans with the flexible spout is the deal for this job.
I just today drained out the old stuff and refilled it with 75-90 full synthetic gear oil.
I figured if it was good enough for semi's pulling 80,000 lbs, then it should be good enough for a 900 lb bike and my fat butt.
But i hope i did it right, i drained and refilled while it was on center stand, not drain on center and refill on side stand.
I used a quart bottle with a piece of silicone hose. I did not remove the saddlebag. On my bike that is too much trouble. i have neon lights, and fiber optic lights on and in each saddle bag. Just too much to unhook just to keep from using a piece of tubing.
I changed the final drive oil yesterday, with spectro Hypiod 80w oil. But when i Drained the used oil, it looked like it was much more than the recomended 140ml. Can it be that the previus owner had the bike on side stand when filling it up?
What can happen if you add to much or to little?
Too little and naturally you might not obtain proper lubrication of the rear drive, too much like sitting on the side stand, do not worry, lot of space in the drive, and it is vented also, do not think you can get it full enough to hurt it.