Oil sludge refers to 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 replaced, sludge will accumulate and the oil will become dirty and deteriorated. If the oil is black, it is likely caused by sludge, so it needs to be changed.

Firstly, is this sludge normal? It should be abnormal. Many people also explain that this greasiness is normal and every engine has it. This statement is incorrect. The engine oil is pumped by the oil pump through a filter to various parts of the engine, and then returned to the oil filter from top to bottom. After impurity filtration, it flows towards the oil pan. This type of sludge can be said to have several times the viscosity of the oil product, and basically does not have the properties of a fluid. It will firmly adhere to the surface of the oil pump filter. The filter cannot effectively suck in enough oil, which will affect the circulation performance of the oil, accelerate the deterioration of the oil, and increase the amount of oil sludge. Oil has a cooling effect in the engine, and insufficient flow can cause local high temperatures in the oil, which is the fundamental reason for the formation of sludge.

The oil filter element will leave residue inside during the oil circulation process. If the oil circulation is normal, the sludge should be inside the oil filter element, rather than adsorbed on the surface of the oil pump filter. Then every time I change the oil, why is it still like this? Turbocharged engines can use low viscosity engine oil, but for regular engines, changing the correct type of oil does not cause oil sludge. Of course, fake engine oil is another matter.

The oil filter element will leave residue inside during the oil circulation process. If the oil circulation is normal, the sludge should be inside the oil filter element, rather than adsorbed on the surface of the oil pump filter. Then every time I change the oil, why is it still like this? Turbocharged engines can use low viscosity engine oil, but for regular engines, changing the correct type of oil does not cause oil sludge. Of course, fake engine oil is another matter.