Performance indicators of oil filters:
1. Pressure drop/flow characteristics: The internal combustion engine oil filter is located between the oil pump and the main oil passage. In order to ensure sufficient oil enters the engine, the pressure drop of the filter when passing through the rated flow rate generally does not exceed the specified value.
When selecting an oil filter for the main engine, it is necessary to examine the rated flow rate of the oil filter and whether it can adapt to the main oil passage flow rate. In addition, in the technical requirements of the filter, the original resistance and the filter must also be measured at the rated flow point. Therefore, the rated flow rate is an important parameter for measuring the capacity of the filter.

2. Bypass valve: When the pressure drop of the filter element is high, it can maintain sufficient oil flow (this part of the oil is unfiltered) to the engine, avoiding engine damage due to oil loss.
When the filter element is working properly, the bypass valve must be in the closed state. In order to restrict unfiltered oil from entering the engine, the bypass valve is usually designed to not open when the pressure drop is below the specified value. When the pressure drop does not exceed the specified value, it is allowed to pass through the bypass valve. There is a leakage amount that does not exceed the specified value, and the value of the leakage amount is generally specified as a percentage of the rated flow rate.

3. Check valve: Spin on oil filter, can be installed horizontally or upside down. In this installation state, the oil inside the filter housing will gradually drain after the engine stops. When the engine starts again, only by filling the filter housing with oil can the oil enter the main oil passage, resulting in a delay in the supply time to the main oil passage, and various moving parts are prone to dry friction and wear. So the housing of the oil filter needs to be filled with oil. In order to prevent the loss of oil inside the engine filter, a check valve that meets the technical requirements must be installed.

4. Pulse fatigue strength: During use, the oil filter will be subject to high pressure shock fluctuations when the engine is in a cold start state. Therefore, it is necessary to assess the ability of the rotary oil filter housing and sealing ring to withstand the specified number of high-pressure wave impacts to ensure the reliability of the filter in use.

5. Filter clogging lifespan: During use, some impurities are trapped on the outer surface of the filter element. As the usage time increases, the impurities attached to the outer surface of the filter element gradually increase, causing an increase in the pressure drop of the filter element. Finally, the filter element is clogged, causing the bypass valve to open, allowing unfiltered oil to flow into the main oil passage of the engine. In order to prevent bypass oil flow during the operation of the filter element, 70% of the opening pressure of the bypass valve is generally used as the end point of the filter element's lifespan.

6. The filter is resistant to high oil temperature: During use, the filter may have high-temperature oil passing through for a long time. In technical standards, it is required that after soaking the oil filter in 135oC engine oil for 192 hours, the filter element should not be delaminated, damaged, and other parts should not have permanent deformation or local damage.

7. High pressure drop: When the filter is blocked during long-term use, it will be subjected to high pressure drop. According to the standard requirements, the central tube of the filter element should not deform under a pressure drop of 0.35Mpa, and the filter element should not have defects such as breakage, perforation, or delamination.

8. Static pressure damage: The filter may be impacted by high oil pressure from the engine under special circumstances during use. According to the standard requirements, the filter should be maintained for 1-5 minutes under a pressure of 1.5Mpa, and there should be no damage or oil leakage on the outer shell.

9. Filtration efficiency: Filtration efficiency is a major item for evaluating the quality of filters. Before the filter element is damaged, its filtration efficiency will improve with the increase of usage time. Currently, most internal combustion engines require the original filtration efficiency of the oil filter to be ≥ 60%.