The reason of filter not filtration or insufficiency of oil input:

1. The oil filter paper element quality bad, the micro pore diameter is undersize

2. The oil hole of the board inside the oil filter is small, whose oil amount supply small

3. Just after installing the filter, the air in the oil path has not exhausted

4. The oil path of the vehicle is blocked, which cannot provide oil or less oil supply

5. North weather cold and temperature is low and the oil flow is bad, which cause difficult to supply oil

6. Bad quality oil and much jelly, it can block the filter paper easily and cause the oil path no oil.

7. The filters without bypass- valve, after using for a while and cannot supply oil, it maybe because the filter paper is blocked and it need to replace new filter

8. If the filters with bypass-valve cannot supply oil during its usage, it is probably because the filter paper is blocked, but the bypass- valve opening pressure is big or it is blocked and can not open.