This increases fuel consumption
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
Does it pay to take the car to a mechanic?
Repair workshop? This is certainly the most popular way to deal with technical problems on our cars. But we can always be sure that the repair goes as it should, and does not appear at this unforeseen problems? Of course not. That is why we should always use a reputable, proven workshop, which will guarantee us that made their work will be reliable and safe for our car. Only such places can make our car back on the road quickly, so sometimes you might even want to pay more for a decent service than to give yourself additional problems.
How much you have to pay for the maintenance of the car?
As you know, the price for servicing the car can sometimes be so high that a big surprise for the owner of the car. Very important is the reasonable choice of service centers, because in this area can often lead to fraud, and the potential client is not able to verify whether they were actually carried out such repairs in the car, for which he paid. The price for servicing the car depends not only on the model of the car, but also on how old our car. What's more, the price for such replacement auto parts is also dependent on the complexity of this process and on how much time the mechanic must devote to bring the car to its former glory.