Your car is "underused".. 24 months only covered 24k km, so 1 month 1k km. So your 5k km top up is in fact a 5 month once affair..
Maybe vaporise lio. What oil u use? When was last oil change?
Come to think of it, 5k km 1L, 20k km is 4 litre of fresh oil lio.. so your engine oil technically fresher than other 325 out there that only top up once every 7~8k km..