As per info I got, you are right to the extent of a petrol accent holding 3.5l of oil incl. the filter. But the 1.5l diesel verna holds 4.7liters of oil. Thats quite a difference.
Oh...my bad. I didn't see "CRDI" in the title But still...
Its 5 litres
Drained and filled up with Mobil Delvac MX - 5 lits. Engine noise had reduced considerably and the pick up is better now.