White smoke when starting cold

My car emits a lot of white smoke when I start it, and the idle is quite rough. The smoke only appears when starting it for the first time after it's been sitting for a while, and the engine sound improves considerably, but it doesn't run perfectly even when the car is warmed up. It's a KIA Cerato CRDI 2.0. Thanks

Greetings...

The cause of that problem could be that oil is leaking into the cylinders through the valves, and it stops when the car starts.
You could fix it by changing the valve stem seals.

It's not very expensive, but you would have to go to a mechanic, as I don't think you can change them at home.

White smoke at startup is almost normal in modern vehicles, as it's condensation from the catalytic converter. The idling issue could be a separate problem. What would be unusual is if the white smoke didn't stop. In this case, the white smoke is water, not oil, since oil is called blue, but it's actually quite transparent. Good luck.

It's very important that you tell us the car's mileage. You should also check the oil dipstick while the car is idling to see if it's venting. I hope this helps, and please let us know how it goes

Check if your spark plugs are burned out