Howardos right here, the system takes around 6.5 litres - can't remember the exact figure. Problem is that the oil cooler setup sometimes retains over a litre probably depending on whether the car is totally level or slightly sloped which seems to be why everyone gets different amounts in.
My first oil change was done on ramps & the car wasn't perfectly level & it took just over 5 litres. The second time, I got it done at MOT time by a friend who was able to get it near level & it took the 6.5l.
Don't forget to use fully synthetic.