It is interesting that the first cars did not have any oil filters at all. In addition, the oils were of very poor quality and needed to be changed very often. The first oil filters appeared only in 1923, invented by Americans Ernest Sweetland and George H. Greenhalgh. They were very simple and consisted of a small strainer attached to the oil pump. They are called ‘purolator’ from the word ‘pure oil later’. At that time, the oil was usually pumped directly to the parts of the engine that needed to be protected and lubricated, and only a small part of the oil passed through the filter, so the majority of the oil was still unfiltered. Nevertheless, it has been seen that vehicle maintenance costs are reduced in this way as well.
It is best to change the oil filter every time the car’s oil is changed. Each type and brand of car has a prescribed number of thousands of kilometers after which the oil must be changed. Also, everything depends on the type of oil used. Newer cars often use very expensive oils that additionally protect the engine, and they can also be changed after a greater number of kilometers traveled.
Today’s oil filters are made mostly of metal wool, paper and wire cloth, which is actually stainless steel. The paper part of the filter is made of paper fleece, which is excellent for very fine filtering. This part of the filter cannot be washed and must be thrown away. When we talk about metallic wool, it is fleece made of metallic fibers. This part of the oil filter performs deep filtering, is very resistant to high temperatures, is very strong and withstands a high pressure drop in the system.
When a significant drop in oil pressure is measured at the oil filter, it is a sign that it is dirty. For example, on a clean filter the drop in oil pressure is about 0.1 bar, while on a dirty one it is several times higher.
There are four types of oil filters. These are pressure, suction, return and breather filter.
Under pressure, filters must be robust because they are most often exposed to the maximum amount of pressure. They are installed in front of the regulation and control devices in order to protect them.
The suction filter is placed inside the hydraulic pump. This is about very fine filtering, however, this type of filter is very difficult to reach and therefore difficult to maintain.
Return filters are usually placed in front of the tank, they are easy to maintain because they are very affordable.
The breather filter is placed in the oil tank itself and purifies the oil entering the system.
Although in recent times it is said that the oil, and therefore the filter, should be changed every 30,000 kilometers, practice has shown that it is still better to do it every 15,000 kilometers, because that way the engine is cleaner and consumes less. Also, the oil changes at the car’s operating temperature of 80 to 90 degrees, and with internal combustion, a harmful residue is created.
Because of all this, it is better to change the oil and the oil filter every 15,000 kilometers driven or, in case the vehicle is used sparingly, every year.