AAAAARRRRGGGHH!!!! Oil leak!!!

[Stanleyf233]

I realise this has probably been covered before, so if any body has had this please hyperlink into a reply the post you used.

Sorry forgot to say it is a 2001 4.4 v8 sport

Driven my X5 to work today, and about two hours after getting there i go back to the car to get something out. While I am walking over to it i can see a dark patch about 30cm across on the concrete. It has developed an oil leak. what i cant work out at the moment and would like some advice before it goes to the garage.

The oil that i checked on the floor appeared to be the same sort of colour as brake fluid but it doesn't seem to be brake fluid. The underneath of the car has a couple of drips of this oil on the bell housing between the gearbox and the engine and also on the rear of the big aluminium stiffening plate and anti-roll bar. there is a black plastic cover about 40mm by 50mm there as well in this area.

Car seems to be driving normally.

My questions are:-
1, What is this oil?
2, What could have gone wrong for it to get out, which seal has gone?
3, How much, part number, ETK drawing should i be looking at?

Thanks for the help!