Being a reasonably well-seasoned bike-on-plane traveller, I'm guessing that my Rohloff/Raven Sports Tour was probably kept in anything but an upright position on out and inbound flights to Andalucia but given that it seems to be a well-documented phenomenen, no signs of any oil leakage. That said, I was little more concerned about those reputedly fragile Raven Sports Tour tubes so didn't really check (any advice on whether I'm effectively subjecting the RST to a form of Russian Roulette by only using a cardboard bikebox appreciated), so assume that any spillage was minimal given as I didn't see any oil on the cardboard boxes.
Whilst on the subject, I've never been charged for excess luggage when taking my bike anywhere though I stress that my load has pretty much always been light-touring, 12kg of luggage, bike and cardboard box (use one of your panniers as hand luggage if you think your are going to be borderline on weight). Always best to check ahead and "know your rights" with the relevant airline as check-in staff are sometimes a bit clueless as to what the regulations are and will start going down the excess baggage route until you make it clear that you're familiar with either their sports equipment or luggage allowance recommendations. At the very worst, expect to have to pay an upfront payment of around £20 when booking for carrying the bike with some of the budget airlines but the national airlines tend to be free.
The only time I've not been able to book a bike onto a plane was when trying to book with Air-France to go Cuba, when I discovered that Air France don't carry bikes to Cuba given an apparently mysterious tendency for them to go missing at Havana airport and a surfeit of related baggage compensation claims I guess. Virgin were happy enough to take the risk though, at no extra cost though they have 3 piece limit (that includes 1 handluggage).
