Gunny!
The rear drive is sealed, as it warms up the air inside needs someplace to go as it expands - vent tube. Putting in to much oil is hard to do, it's full when it reaches the bottom of the fill hole, any more and it comes pouring out as you put it in.
FWIW, mine leaked out the top, too. It did it with just 580 miles on the odometer (started blowing out on a 200 mile trip). Checked the level, it was fine. When I told the service dept. about it at the 600 mile break-in maintenance the next day, he said they most likely put in too much final gear oil during assembly. Hasn't leaked since (now at 4K with several 400+ mile days).
Only way to do that is on purpose man, and it'd require 2 people (one holding the bike leaned to the right). The more likely scenario would be to UNDERFILL the final drive, if somebody was to do that while on the sidestand. Later.
Most definitely. When I have had my final drive off and it has not been upright I have had oil leak from the vent cap.
