SKutorr, you brought up a good point about leaks that I have known for a long time and have discussed with master BMW motorcycle mechanics concerning synthetic oils: They can "Cause" leaks almost immediately in areas that have never leaked and especially on older bikes/ scoots. Apparently, DINO oil causes 'seals' to 'swell' and stay tight for the most part. Once synthetic oils are used those same seal start to shrink and the oil seeps or weeps out. New bikes/ scoots/cars have tighter seal that are more elastic and form fit better.
Now, at least to me, here's where it gets interesting and has been proven: In most cases a small leak that appears after using synthetic oil for the first time, can or may stop after the use of Dino oil again.
The affect of chemicals on rubber or elastic seals can be easily seen by using carb/ fuel injection cleaner on an old 'O' ring that fit in a groove in a carb for instance: Soak the 'O' ring in carb cleaner and within a few minutes it will grow enough to not fit at all in it's last application. Liquid Hydrocarbons in Transmission fluid helps keep them from leaking in cars and stop leak has lots more in volume of the stuff.
By the way, thanks for the heads up about the leaking seal problem---I will just add that to the numerous others that must be done by dealers before they sell them (Supposedly) or never taken care of at all by someone selling a used C600/ 650
Sam