In the olden days of British Motorbikes, oil leaks were a way of life. If you ever get to visit the Transport Museum in Glasgow, you'll also spot trays under the old cars to catch the odd drips that come with old engines. I don't remember leaks under the bikes they have, but I guess it depends whether they are runners and are oiled up.
My daughter spotted a damp patch under the R1100RS on Friday, and right enough after a bit of checking on my hands and knees it looks like a small leak at the sump plug. I gave it a bit of a tighten, but it is still leaking. Having checked the standard problems with the bike, it appears that corroding alloy washers are a common problem. It will need an oil change to fix though, so I'll be calling the local bike fixing place to get them to do it. It's years since I did an oil change and I don't have the kit anymore, and I reckon buying it would cost as much as getting it done.
Anyway, went out on the bike this morning and it is running well. I just need to keep working on my riding skills :)