The color of the exhaust gases will tell you about the problems of the fuel system of the car.
The black (dark gray) color of the smoke signals a very high fuel supply, inefficient operation of the turbocharger, a clogged air filter, wear and contamination of the injectors, or improper installation of the injection pump injection timing. Black smoke can also indicate low qualitydiesel fuel used.
Blue (bluish-gray) smoke indicates that engine oil burns in the engine cylinders, poor compression or oil scraper piston rings work inefficiently.
White (grayish-white, gray) smoke indicates that the engine is poorly heated, or the fuel leaks from the injectors or the fuel enter the oil due to leakage from the “return” of the injectors, or the injection pump injection point is shot down.
In the end, we will give a piece of rather banal advice – refuel with high-quality diesel fuel. High-quality fuel will ensure good engine traction and reduce fuel consumption. With high-quality fuel, the probability of damage to the fuel system is reduced, which means that the engine will last longer. And this is also a significant saving of money.