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Update:
The brown color of coolant is due to hydrocarbons in cooling system.
Wnen car working there are air bubbles that coming from radiator constantly and rough idle.
Either it is headgasket failure either the engine head or block has crack.
Will see when repaired

do you see any rough working of the engine? The temperature is ok?

Temperature is ok. The main problem is the rough idle.
Also some smell from exhaust when the car is on the pressure.
And if I revving the engine in limit there is a smoke too

How much oil does it burn? In my opinion don't do anything before it falls apart. It may stay this was for a long time. Rough idle by saying?

Oil consumption is about 500-600ml every 5000km with normal driving, with aggressive little more.
The idle is rough meaning that there is a little vibration and sometimes the revs drops and re-coming to the normal. I think that means compression loose in some cylinder.

Sounds like headgsasket to me man. Do you have oil in your coolant yet? If burnt petrol is getting in your coolant This also means that coolant is getting into your engine and burning this is why you have smoke in your exhaust. This could also explain the crappy engine running if the coolant is coating spark plug or valves, etc. I think you need to take the head off and investigate.

Let us know how it goes man.