@ismailmarwat
If the car engine is car, and the current oil inside the engine turned BLACK in color, then I suggest ask the person from whom you bought this car, what oil he has been using in this car? If he is stick to 1 oil for the last many months/yrs, so it would be better for you to stick to the same engine oil, rather than changing.
If your oil turns black, then remember that ZiC A type oils are purely synthetic and wud ruine your engine.