Motor oil lubricates moving parts in the engine. The oil also drains heat away from hot spots and transports wear particles away. These particles have to be removed from the oil, otherwise they would get into bearings and between sliding surfaces. That would cause wear. The oil filter is responsible for removing these particles.
Oil filters come in two sorts: bare filter elements and complete bolt-on cartridges. The bare elements are made of impregnated filter "paper", containing miniscule pores that trap the dirt particles. To increase capacity and decrease flow resistance, the paper is folded like a harmonica, so a large amount of paper can be put in a small filter. The paper is moulded into a plastic sealing ring, sometimes covered by a metal lid.
The cartridge type oil filter has a built in filter element and is usually equipped with a non-return valve and a pressure valve, which protects the filter element from bursting when the pressure rises too high, due to low temperatures or a clogged, saturated filter.
Even though oil filters seem quite simple car parts, there's a huge quality difference between different brands. Cheap filters often use simple "2D" paper, with pores that block dirt particles of all sizes on one level. More expensive filters use layered or "3D" paper, able to filter the bigger particles in the first layers and the small ones in the deeper layers, leaving more pores open to let the oil run through. Cheap filters often count less "harmonica blades", so there is less paper and less filtering capacity. In cartridge filters, the pressure valves on cheap models may fail or open at the wrong pressure, letting unfiltered oil pass. Failing non-return valves let oil flow back into the sump when the engine is shut off. In that case, it will take longer for the engine to rebuild oil pressure after starting, causing wear.
Looks can be deceiving. You can't judge the quality of a filter by its appearance. It is best to rely on proven, renowned brands like Nipparts. Nipparts has been making high quality oil filters for decades. The name "Nipparts" is a guarantee for OE-matching quality, excellent warranty and an excellent availability for Asian cars.
Nipparts Oil Filters
- High quality paper
- High quality molds
- Excellent build quality
- Made to OE standards and specifications