Oil & Oil Filter change.

[darrsi]

You will find that you will have to undo & do it up with a ring spanner as you can't get a torque wrench or socket on it due to the frame. Just nip it up don't be tempted to over tighten as you will strip the threads.

That was my earlier point about not going mad tightening it up, you can't get a socket on the nut so unless you've got some fancy contraption then nipping up as bandit says is more than enough. If it was to leak, which it won't, then simply nip it up a little bit more.
Just make sure the ring spanner is on properly otherwise it will quite easily round off or damage the soft hex head of the bolt......been there, done that before.  :o