Stu Get 2*5 Litters of Oil Which one were you thinking of usesing?
Texco Havilen Is fitted By Nissan, Halfords Sell it at a good price!
Drain oil and Take Filter off and Before Refitting Filter, Fill about 3/4 full of Oil this does take a few minutes (the Reson for doing this is So the system is Primed) And now for the tricky part get it on with out spilling the Oil
Then put about 4 Litters in and Start checking the Dip stick and soon as it is on the end of the stick add in 1/4 litter amounts checking as you go!
To answer your Question Aprox 5 Litters This is only an Aprox because it depends on How much Oil you can get out! there always be some left in the Engine which in it's self is no bad thing if you get your oil real hot drive in and drop it get filter off with out burning your self you will get more out!! so you will need to put more in!!
You will need to check the oil level after you have run it and top up!
I have been told that you can over fill about half a litter for track usage to over come Slop with out any problems but not needed for road usage!
I am doing mine before saturday and as this is the second time I have 3/4 of a can form last time so only one new can is needed