Practical Automotive Maintenance: Oil Filters

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Oil Filters

08.31

00:00	As discussed in the last module, our oil is responsible not only for lubricating, but also keeping our components clean.
00:07	As the oil collects combustion byproducts and debris, it starts getting dirty.
00:12	So, how do we keep the oil itself clean to maximise its lifespan? And this is where oil filters come in.
00:19	An oil filter is exactly what it sounds like.
00:21	It filters the oil that's circulating through the engine to capture any particles caught in our oil film and prevent them from travelling around the engine, potentially causing damage.
00:31	The most common style of filter used by all OEMs is what's called a full flow filter, which filters the oil supply before entering the oil galleries.
00:41	Full flow filters come in two main types, spin -on and cartridge.
00:45	While both serve the same purpose of removing contaminants, their design and installation methods do differ.
00:51	Spin-on filters are a self-contained unit with a metal canister housing, the filter media and a sealing gasket on the mating surface.
01:00	Cartridge filters on the other hand consist of a replaceable filter element which is housed inside a separate reusable casing, usually made of metal or plastic.
01:10	This casing uses an o-ring seal and screws into a filter housing on the engine.
01:15	Oil clearances in an engine are very fine, so even small debris or particles may end up scoring bearings or crankshaft journals.
01:23	A filter's ability to remove fine contaminants is measured in microns, short for micrometres, which is a unit of measurement equal to one millionth of a metre, which is about the thickness of a human hair.
01:36	In oil filtration, micron ratings refer to the size of particles that a filter can remove from the oil.
01:42	The lower the micron rating, the finer the filtration.
01:46	A 20 micron filter captures particles 20 microns or larger, and a 10 micron filter captures even smaller contaminants, down to 10 microns and, so on.
01:57	At this point you might be thinking it's just a case of the lower number the better, and while yes, a lower number does indicate better filtration, this can negatively affect oil flow, as finer filters are harder for the oil to travel through, particularly when it's cold.
02:12	This isn't something that we generally have to worry about though, as the filter manufacturers do all the hard work for us to ensure proper flow and filtration, but it's worth mentioning that not every brand will have the same flow characteristics if it's primary focus is particle filtration.
02:28	Regardless of what style oil filter we have, they'll also contain an internal oil bypass valve.
02:35	If the filter element becomes clogged with debris, this reduces the oil's ability to pass through the filter and into the engine, which can starve critical components of oil.
02:45	In this situation the oil pressure inside the filter would increase as the pump is supplying more oil than the clogged filter can flow.
02:53	The increase in local oil pressure causes the bypass valve to open, allowing oil to flow directly into the engine without passing through the filter, preventing oil starvation which could cause severe damage to the engine.
03:06	While passing unfiltered oil through the engine is clearly not ideal, it is the lesser of two evils compared to starving the engine of oil completely.
03:15	The filter that suits the vehicle is specified by the manufacturer and can be found in the owner's manual or again, just like the oil itself, can be searched online with the manufacturer filter guide.
03:26	Both spin-on and cartridge filters are likely to have a regular and a performance option, depending on the brand.
03:32	The regular option contains cellulose filters, which are the common type of filter in both OEM and aftermarket applications and are appropriate in most situations.
03:42	The term cellulose filter refers to the filter media or element, which is typically made up from cellulose fibers and resembles a paper style element, sometimes supported by a metal or plastic mesh with paper or plastic end caps to help keep its shape.
03:57	Cellulose filters are cheaper to produce and are commonly used by OEMs and in non-performance applications.
04:02	They typically last about eight to ten thousand kilometers before requiring replacement, but they do have the ability to last longer.
04:10	With that said, this isn't recommended as extended service intervals could cause blockages and a lack of filtration or oil flow.
04:18	We will also have the option to select a performance filter.
04:21	These are typically made from a synthetic blend of micro glass fibers or synthetic fiber blends.
04:27	These are much finer and more uniform than traditional paper or cellulose filters.
04:32	The microscopic glass fibers create a dense, but highly porous filtration structure, with some claiming to trap 94% of contaminants at the 10 micron range and up to 99% of particles in the 20 to 30 micron range.
04:46	Because of this highly porous yet dense filtration, these filters are still able to supply proper oil flow to our components while having finer filtration.
04:55	Synthetic filters also claim to be able to hold a larger volume of particles without clogging.
05:01	In the previous oil specifications module we mentioned that cars running alcohol fuels can suffer from oil contamination with ethanol or methanol ending up in the oil and causing it to break down due to its solvent effects.
05:14	This has a flow-on effect to our oil filters as well and depending on the amount of alcohol fuel that's in our oil, this can cause cellulose oil filter elements to break down.
05:24	Some manufacturers claim that all their filters are compatible with alcohol fuel contamination.
05:29	However, synthetic filters are a safer choice on cars that use alcohol fuel as the synthetic micro glass fibers used are more resistant to the solvent properties of the alcohol fuels, making them less likely to break down and clog.
05:44	With, so many brands out there you might be wondering if it's worth getting a filter directly from the OEM and this will be a case-by -case situation depending on the vehicle and some of the factors that we just discussed.
05:56	In most cases though car makers will actually outsource the filter manufacturing to a large established filter brand like Denso or Mahle with specific requirements to suit their engine.
06:07	These OEM filters are typically cellulose style and are deemed adequate for most applications including performance engines.
06:15	Where it can be beneficial to switch to an aftermarket application is when we remote mount a filter.
06:20	This might be needed to provide more flexibility with packaging if we're engine swapping a car and need to work around different constraints for easier access and it also allows for a substantially bigger filter to be used.
06:32	For example, on the HPA SR86 race car we moved to a Fram HP1 filter which is roughly three times the size of the stock SR20 filter.
06:42	The benefit here is much larger filter surface which not only has a larger capacity, reducing the likelihood of clogging, but is also designed to be stronger and handle higher than stock oil pressures.
06:54	Each brand will have different characteristics and filtration claims.
06:58	Without scientifically testing each one we can simply deduce that an OEM style filter will be suitable for most stock and performance applications and typically last eight to ten thousand kilometres before replacement.
07:10	The only products we'd recommend staying away from are the cheap parts store aftermarket replacement options as quality can be questionable in some of these filters.
07:18	Let's summarise the key points in this module before moving on.
07:22	An oil filter's job is to remove contaminants like dirt, metal particles and combustion byproducts.
07:28	Most modern engines use full flow filters which clean the engine's oil before it enters the engine's main galleries.
07:35	Filters come in spin-on or cartridge types with the correct one specified by the vehicle manufacturer.
07:41	All filters include a bypass valve that ensures oil continues to flow if the filter becomes clogged, preventing engine damage.
07:49	Filtration efficiency is measured in microns.
07:52	The smaller the number, the finer the filtration.
07:55	Standard filters typically use cellulose media while performance filters use synthetic or micro glass fibres.
08:02	These offer a finer filtration, better flow and longer service life due to the greater contaminant capacity.
08:09	Most OEM filters are cellulose based and suitable for regular and light performance use.
08:15	However, synthetic filters are better suited for racing, remote mounted systems or alcohol fuelled engines as they resist solvent breakdown that can clog cellulose filters under high alcohol exposure.