Thanks mrmum, at 18 GBP S&H, it's well worth ordering in the UK. 12 bottles of 15W50 cost 66 GBP at Flightstore vs. ca. 95 GBP in Germany. They will get my business next time.
For Lycoming engines, you need either an oil with additives according to Lycoming's service bulletin or a plain oil with an extra bottle of additives. Here's the service bulletin:
http://www.lycoming.com/support/publ...fs/SI1014M.pdf
AeroShell 15W50 or W80 complies with Lycoming's SB whereas the plain 100 or 80 would not. W80 is a monograde oil and not suitable for cold temperatures.