Not sure on the 1.6, my 1.8T takes about 4.5l, as guess I would say a 1.6 would take less but only getting a 4L bottle would be cutting it fine IMO. Check the handbook the oil capacity should be in there somewhere. Either way get a 4L bottle and a 1L bottle, keep the 1L in the car for roadside topups etc, least then you know it will be the same kind of oil. 5W30 will be fine, make sure you get good quality stuff and not supermarket crap.