I own a 99 boxeyed since earlier this year and I'm really happy with it so far. The only thing I came across was exactly the incident described here.
I was riding through the dolomites a few days and the oil light suddenly started to come alive when going uphills and revs above ~6000. It was not even just a flicker but a steady light unless i released the throttle (i only tried for 1 or two seconds though). I was very anxious since i only have basic mechanical knowledge. At the same time I was confused, knowing it was a oil-level - not pressure - indicator on that bike so I'd never expected that thing to come on while driving in the first place (no idea how a "oil level" can be indicated/measured while the sludge in there is tossed around at ridiculous speed).
I always try to keep an eye on the basic maintenance indicators - like the oil glass - and the level visible was about half way between min and max at that time - so i was worried that this wouldnt be the problem but something else (worse?).
I payed the next available bike mechanics a visit and the first thing he told me was, that this is a known yamaha thing - the oil lvl indicators are rather sensitive and tend to warn you rather early if the oil level is not near the max lvl ... he then just filled her up again (probably about the amount of 1 or two eggcups ... metric ones in my case, i assume
) and sent me off into the mountains again.
No red lights anymore since, so i guess that was really it.
