All cars are fitted with a bunch of different filters to keep the air and fluids that the car needs run nice and clean. The car you drive, at a minimum will be fitted with an oil filter, an air filter, a fuel filter and a pollen/cabin filter.
You’ll no doubt have been told that you have to change your cars filters when it gets serviced but why? What will happen if you don’t bother? Another thing to be aware of is that not all filters are the same, the quality can vary drastically and to the naked eye it can be difficult to spot a poor quality filter.
In this blog we’re focusing our attention on the most commonly changed filter, the oil filter.
How the oil filter works:
There are 2 main types of oil filter, the spin-on type and the cartridge/element type, they both do exactly the same thing, just in slightly different ways.
The function of the oil filter is to continuously clean the engine oil of minute carbon, soot and metallic particles that naturally break free from the moving engine components as you drive. If left unfiltered the engine oil would very quickly become ineffective and would actually start to do harm to your engine (imagine these particles being a bit like the exfoliant your wife uses in the bath – very abrasive and scratchy, not at all what you want in your engine!) These particles actually start to wear away the moving components inside your engine – in particular the bearings. Eventually the wear will become so great that the engine is likely to seize. If that happens you’ll either be looking for a new engine or a repair bill well into the thousands.
This diagram shows a cutaway of a typical ‘spin-on’ oil filter. The blue arrows illustrate the direction the oil flows around the filter.
The oil filter has a built-in safety mechanism in the form of the bypass valve. When the filter gets old and the filtration material gets clogged up with all these carbon and metallic particles the bypass valve opens up (at a predefined pressure) so that the engine still gets a constant supply of oil. The trouble is, the oil is now completely unfiltered.
The Difference Between a Good & a Bad Oil Filter:
The exploded view of the oil filter below illustrates all the separate parts that go into a high quality oil filter. Each component is made to the correct specification is made of the correct grade of material, as specified by the original vehicle manufacturer.
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