The oil filter housing is made of aluminum and includes a filter element, as well as an anti-drain and bypass valve. Structurally, it consists of two halves with a removable heat exchanger; special threaded fasteners in the form of a six-pointed star interconnect them. Between the heat exchanger and the housing, there is a gasket, which ensures the tightness of the connections. If an oil leak is found in the area of the housing, then most likely the gasket is out of order, in rare cases the housing itself may be damaged.

The main operational principle of oil filter housing cover

The TOPRAN brand Cover, oil filter housing closes the drain and opens it when you change the oil, so the filter housing runs empty.

1. SHARAN (7M8, 7M9, 7M6)
2. A3 (8L1)
3. A3 / S3 (8L1)
4. ALHAMBRA (7V8, 7V9)
5. CORDOBA (6K1, 6K2)
6. CORDOBA Saloon (6K1, 6K2)
7. IBIZA II (6K1)
8. IBIZA Mk II (6K1)
9. OCTAVIA I (1U2)
10. POLO CLASSIC (6V2)
11. FLIGHT CLASSIC (6V2)
12. DERBY CLASSIC (6V2)
13. INCA (6K9)
14. GOLF IV (1J1)
15. GOLF IV (1J1, 9B1)
16. GOLF Mk IV (1J1)
17. LT 28-35 II Bus (2DB, 2DE, 2DK)
18. LT Mk II Bus (2DB, 2DE, 2DK)
19. LT 28-46 II Platform/Chassis (2DC, 2DF, 2DG, 2DL, 2DM)
20. LT Mk II Platform/Chassis (2DC, 2DF, 2DG, 2DL, 2DM)
21. See more in applications

If it is missing, the oil flows unused back into the oil pan, even when the engine is running, and you lose oil pressure, so you have performance problems, and every time, when you start the engine, there is an oil gap, the filter housing must be completely bled again.