Think from memory they take around 5 litres if changing the filter as well, if not then slightly less like 4.8 or something, should be on here somewhere if you do a search, or in the handbook if you've got one. It's recommended to change the filter at same time as well. I would just fill up around 4 litres, run engine for a bit to let it circulate, switch off, then small top-ups afterwards whilst checking the dipstick until it reaches the Max mark mate.