Oil Filter
An oil filter traps metal particles, soot and dirt in the engine oil so clean oil circulates through the engine, and is renewed at every oil change.
Prepared by the Bicops Technical Content Team · Last updated:
Shop Oil FilterWhat does it do?
While the engine runs, micron-level metal wear occurs in the bearings and on the cylinder walls, and combustion soot also mixes into the oil. As the oil pump circulates the oil, those particles are caught in the filter. If the filter clogs, its bypass valve opens and the engine runs on unfiltered oil — a deliberate emergency design to protect the engine, not a permanent condition.
When should it be changed?
The oil filter is always changed together with the engine oil, at the manufacturer’s service interval: typically 10,000-15,000 km for petrol engines and 10,000-20,000 km for diesels. In short-trip city use the engine often never fully warms up, so the oil degrades faster and the interval should be shortened.
Cartridge or spin-on?
The classic type is a complete spin-on filter with the element and valves inside a metal housing. Most newer engines use a cartridge type where only the paper element is replaced; with that type the cap seal must also be renewed. The safest way to pick the right type is the car’s OEM number, since different engine options of the same model can use different filters.
Frequently Asked Questions
Can the oil filter be changed on its own?
Technically yes, but it makes little sense. Some oil drains out when the filter is removed, and already-contaminated oil loads the new filter quickly; the two are replaced together.
What happens if the filter is not changed?
Once the filter clogs, the bypass valve opens and the engine starts running on unfiltered oil. Wear particles reach the bearings, leading over time to expensive bearing and turbo damage.
Do aftermarket oil filters harm the engine?
Aftermarket filters from known manufacturers that match the car are safe to use. The risk lies with unbranded cheap filters whose valve design and filtration rating do not suit the engine.