reduce smoke BMW Motor oil is a lubricant
Motor oil is a lubricant used in internal combustion engines, which power cars, motorcycles, lawnmowers, engine-generators, and many other machines. In engines, there are parts which move against each other, and the friction wastes otherwise useful power by converting the kinetic energy to heat. It also wears away those parts, which could lead to lower efficiency and degradation of the engine. This increases fuel consumption, decreases power output, and can lead to engine failure.
Lubricating oil creates a separating film between surfaces of adjacent moving parts to minimize direct contact between them, decreasing heat caused by friction and reducing wear, thus protecting the engine. In use, motor oil transfers heat through convection as it flows through the engine by means of air flow over the surface of the oil pan, an oil cooler and through the buildup of oil gases evacuated by the Positive Crankcase Ventilation (PCV) system.
In petrol (gasoline) engines, the top piston ring can expose the motor oil to temperatures of 160 °C (320 °F). In diesel engines the top ring can expose the oil to temperatures over 315 °C (600 °F). Motor oils with higher viscosity indices thin less at these higher temperatures.
Coating metal parts with oil also keeps them from being exposed to oxygen, inhibiting oxidation at elevated operating temperatures preventing rust or corrosion. Corrosion inhibitors may also be added to the motor oil. Many motor oils also have detergents and dispersants added to help keep the engine clean and minimize oil sludge build-up. The oil is able to trap soot from combustion in itself, rather than leaving it deposited on the internal surfaces. It is a combination of this, and some singeing that turns used oil black after some running.
Rubbing of metal engine parts inevitably produces some microscopic metallic particles from the wearing of the surfaces. Such particles could circulate in the oil and grind against moving parts, causing wear. Because particles accumulate in the oil, it is typically circulated through an oil filter to remove harmful particles. An oil pump, a vane or gear pump powered by the engine, pumps the oil throughout the engine, including the oil filter. Oil filters can be a full flow or bypass type.
Źródło: https://en.wikipedia.org/wiki/Motor_oil
How to recognize a good mechanic?
Each car from time to time need of repair - minor defects is quite a normal thing. It happens also that the car must travel a serious review. Whatever the situation, you might want to have a trusted mechanic who well knows his job. But how to find it? A good solution is to ask your friends if they could recommend someone suitable. Reputation in such a case often provides the highest quality services. In addition, if a mechanic can quickly find the cause of problems with the car and is able to immediately determine the extent of repairs needed and valued service and the cost of parts - most likely we are dealing with a trustworthy expert.
Why do car repairs are readily carried out even by amateurs?
As you know, car servicing and replacement of parts is often very expensive. It is no wonder that more and more people try their own or with help from friends or literature available to carry out such repair. If our car really should now be scrapped, there are several possibilities for its development. Popular is the sale of car parts that can be removed from an unused car. There is a considerable demand for this type of offer. Often used parts are much more readily purchased by the owners of others, especially older car models.