Sludge is the fuel residue inside the engine. Also known as carbon sludge, it remains in the engine oil and is filtered by the oil filter. But if the oil or oil filter is not changed, sludge will build up and the oil will become dirty and spoiled. If the oil is black, it is most likely caused by sludge, so the oil needs to be changed.

First, is this sludge normal? It should be abnormal. There are also many people explaining that this kind of oiliness is normal and every engine will have it. This statement is wrong. The oil is pumped by the oil pump to various parts of the engine through the filter screen, and then returns to the oil filter element from top to bottom. Impurities are filtered and flow to the oil pan. This kind of sludge can be said to be several times the viscosity of oil, basically does not have the performance of a fluid, and will be firmly adsorbed on the surface of the oil pump filter. The filter cannot effectively absorb enough oil, which will affect the circulation performance of the oil, accelerate the deterioration of the oil, and increase the amount of sludge. Engine oil has a cooling effect in the engine, and insufficient flow leads to local high temperature of the engine oil, which is the root cause of sludge.

Oil filters leave residue in the filter as the oil circulates. If the oil circulation is normal, the sludge should be in the oil filter element, not adsorbed on the surface of the oil pump screen. Then every time the oil is changed, why is it still like this? Turbocharged engines can use low-viscosity oil, but for normal engines, replace the correct type of oil, and the sludge is not caused by oil problems. Of course, fake motor oil is another matter.

Oil filters leave residue in the filter as the oil circulates. If the oil circulation is normal, the sludge should be in the oil filter element, not adsorbed on the surface of the oil pump screen. Then every time the oil is changed, why is it still like this? Turbocharged engines can use low-viscosity oil, but for normal engines, replace the correct type of oil, and the sludge is not caused by oil problems. Of course, fake motor oil is another matter.

The task of the air filter is to filter the suspended particles in the air entering the cylinder to reduce the wear of the cylinder, piston and piston ring. Of the three media required for the engine to work, air has the largest volume and comes from the atmosphere. If the air filter cannot effectively filter the suspended particles in the air, the lighter one will accelerate the wear of the cylinder, piston and piston ring, and the heavier one will cause the cylinder to be strained and shorten the service life of the engine.

In theory, the service life and maintenance interval of an air filter should be measured by the ratio of the gas flow through the filter element to the gas flow required by the engine. When the flow rate is greater than the flow rate, the filter works normally; when the flow rate is equal to the flow rate, the filter should be maintained; when the flow rate is less than the flow rate, the filter can no longer be used, otherwise the working conditions of the engine will deteriorate. It got worse and worse and couldn't even work.
In actual work, when the air filter element is blocked by suspended particles and cannot meet the airflow required by the engine, the engine will have abnormal working conditions, such as roaring, slow acceleration (insufficient intake air volume, insufficient cylinder pressure), The work is weak (the mixture is too rich to cause incomplete combustion), the water temperature is relatively high (the combustion continues when entering the exhaust stroke), and the smoke becomes thicker when the exhaust accelerates. When these symptoms appear, it can be judged that the air filter is clogged, and the filter element should be removed in time for maintenance or replacement.
When maintaining the air filter element, pay attention to the color change of the inner and outer surfaces of the filter element. After dust removal, the outer surface of the filter paper is clear and the inner surface is bright, and the filter element can continue to be used; if the outer surface of the filter paper loses its original color or the inner surface becomes dark, it must be replaced.

In the instruction manual of the air filter, although the mileage or working hours are specified as maintenance or replacement data. But in fact, the maintenance and replacement cycle of the air filter is also related to environmental factors.
For cars that are often driven in a dusty environment, the maintenance or replacement cycle of the air filter should be shortened; for dusty cars, the maintenance or replacement cycle of the air filter is sufficient. Appropriately extended.
In actual work, many drivers and maintenance personnel act mechanically according to the regulations, without flexible grasp of different factors such as the environment, and insist on waiting for the mileage to reach the standard and the engine working status to be obviously abnormal before performing maintenance. It should be noted that if maintenance is carried out at this time, not only the losses already caused cannot be recovered, but also greater harm will be caused. What's more, individual drivers don't even know that the air filter will fail, and continue to use it as long as the appearance is not damaged.