I dont know what kind of engine Cultus has, but, oil change is totally Unnecessary before 5,000 kms for Any New car, if you keep on changing oil at 5,000 kms then there is no worry.
The cars that i have kept in the last 15 years, only Mehran needs oil change at 3,000- 4,000 kms, others go fine until 5,000.
Currently i change my spectra's oil at 7,000 kms, which mostly includes long runs, the condition of exhast is grey, no carbon comes on my finger tip Removing the oil cap, shows a clean shining inside but yes i change its oil filter with every oil change with its original one.
About my Daewoo, its now 1,55,000 kms done, has a grey exhaust on cng, throwing water, oil change at 5,000 to 6,000 kms with its original oil filter.