Some info from Purolator, that might challange our minds & prove contrary to what we might believe about how the oil filter media works to remove particles & no it doesn't strain/filter them out. So media composition & fiber spacing & size is really important in order that particles be removed by the oil suddenly changing direction as it flows over the media fibers & the particles being flung out by the sudden change in flow direction & then with held in the media material. OIL FILTERS EXPOSED Precision Engine

 

Well, THAT was all a "certainly-un-biased" explanation of oil filtration, and written by a typical automotive writer.

Anyone who really wants to learn about the subject would do well to hang around BITOG for a while, where some true professionals, with no brand-specific loyalties, hang their hats.

That "reporter" just took the party line as gospel, and didn't really do any homework on the subject. Such is the modern automotive "journalist".

Sorta' like watching Spike TV's automotive "how-to" programming........

Pablum.

Please note, all the above is not to be considered a reflection of FTEs "pawpaw", but on the referenced article's author, Mike Mavrigian.

Pop

 

Yah he was sorta promoting Purolator, as they were feeding theory info to him for the article, but getting beyond that & looking at the filtration theory of centrifugal force seperation of particles in a medium, by its quickly changing direction as it flows over the filter media fibers, is probably a new/novel idea for most folks on how a filter media really works, as most of us probably visualize the particles as being screened out, not flung out by centrifugal force, as the oil flows over & around the media fibers. Doesn't make any difference who makes the filter, or flter media, the filtering theory is the same!!! Now how well it does this job, will show in the UOA particle counts & some filters have been shown to perform much better at this than others!!!!

I have an old 1950's Briggs & Stratton engine that has an oil bath air cleaner on it, like the one described in the article & I remember automotive oil bath air filters too. Any way they worked the same way by having the air being sucked into the engine quickly changing direction as it flowed over & around the filters oil wetted fibers & the dust being heavier than air, would be flung out by centrifugal force & stick to the oil wetted fibers & drain back to the air filter oil sump, located in the housing base, when the engine was shut down. That oil sump would load up with plenty of muck from the air filter over time.
My Troy Built mower 05 Briggs 21hp V Twin air filter, uses an oil wetted foam prefilter to trap the big stuff, so the paper filter doesn't get dirty & still looks new after 7 years!!!!

Some oil bypass filters use centrifugal/spin force, to fling contaminates out of what they're filtering, so the theory has been around for a long time, but not often thought of in the right context when we think of how our oil filter media really works.

Our vehicles air filter media is slightly oil wetted, to help make the particles stick to the filter media fibers, we just no longer have to use an oil sump in the filter housing to wet the media.

 

This does explain why those expensive "permanent" screen type oil filters are such a bad idea. Oddly, my Yamaha motorcycle comes with a fancy srceen from the factory. Traditional folded media filters are available in the aftermarket. Yamaha may be worried about the capacity of that tiny filter, due to transmission and clutch sharing the same oil supply with the engine.

 

This explanation isn't very good, IMO. Or maybe Purolator has a different design. Or maybe the author misunderstood, considering that, while technically correct, he's misleading saying Purolator invented the spin-on. Yes, they invented one, but abandoned it because it wasn't commercially viable. Wix holds the patent, from 1954, for the fist commercially viable spin-on.

In any case, MANN filters, and I'm sure others, actually filter the oil.

Also, if you look at a filter with the bypass valve in the threaded end, and so a solid covering at the dome end, they couldn't work as described unless the oil went in and out of the same holes.
The other thing that makes no sense, based on the article, is the bypass valve. Why would you need one? If the oil just passes over the media, and not through it, the bypass valve would never open, unless the filter canister were completely full of dirt. On my oil bath air cleaners (used in the article as an analogy) they keep passing air, even when the oil is filthy. They don't need a bypass valve.

 

If we can stay focused on the filter media construction & try to visualize the shape of the material, one can begin to get a grip on how the centrifugal forces can fling solids out of the flow, as oil changes direction as it moves around the media fibers.
So, the fiber construction, shape, density, ect, all make a difference in how well a filter media does its job.

How well the filter media does this job & how well the media holds on to the particles after they've been separated from the oil flow, can be detected by a UOA particle count.

After an oil & filter change, the filter doesn't have much to do, as the oil is clean. After a filter is used for a while, it'll get more efficient at filtering, as the media pores clog up, so the media type (surface, or depth loading) & media surface area (the amount of filter media in the filter), bypass valve psi rating, begin to come into play in whether the filter goes into the bypass mode when we get crazy & go WOT to blow some carbon out while enjoying the thrust, or on those cold morning high rpm starts, etc.

Here is Motorcraft's take on the why for base end by-pass valve location & you can follow the flow arrows to see how it works. http://www.bullittarchive.com/5000/5...arison_Kit.pdf

 

I understand change in direction of air or fluid flow will cause larger/heavier particles to come out of suspension.
So of course a filter will cause some of that. That's why you can end up with a little mound of sludge in the dome end of a filter. For oil filters, I observed that many years ago changing canister type filters.
However, smaller particles won't and have to be filtered out as they pass through the media.
My take on the article is that it states that no filtering occurs from oil passing through the media. That is contrary to MANN's video and oil filter design.

I also understand the reason for the bypass valve in a full flow filter, but again, what would be the need if the oil never passes through the media? There's nothing to bypass.
It could be the author has gotten full flow filters (our common spin-on) and centrifugal filters confused.

I just got off the phone with an engineer at Wix and he actually laughed when I told him about the article. He stated unequivocally that the oil does, in fact, pass through the filter media for filtering as illustrated in the MANN video.

Edit: Baldwin says the same thing when I called their tech line, the oil is filtered by passing through the media.

 

The article doesn't suggest that the oil Doesn't pass through the filter media, its talking about what happens to the debris in the oil & how the filter media removes & stores it, to clean the oil as it passes over & through the media fibers on its way through.

For instance paper media fibers & pore/hole sizes are different than synthetic media fibers, which are more consistant in size & shape & pore size, so they load & flow differently than a paper media.

Cellulose, in a filter enables it to absorb & hold onto moisture that's circulating in the lubricant. So it has its place in filtering media, especially for those of us that mostly short trip, such that our engine oil doesn't reach operating temp to boil off condensation. Lots more than just particle size removal to consider, when choosing a filter to best suit our operating conditions & drive cycle.

The bypass valve is needed when the oil viscosity, or filter loading restrict flow during high demand/high rpm times. So it opens to maintain needed oil volume flow, but when the bypass valve opens, the oil that passes through it, isn't filtered, no matter which end of the filter its located. So Ford suggests that in inverted filter mounting positions, a base end bypass valve offers less chance for loosely attached debris being washed off the filter media as oil flows past, or stirring up sediment that's settled out in the dome end of the inverted mounted filter, as the dome end bypass valve opens.

 

I know it doesn't suggest it. it says it out right I don't know how that's not saying the filter doesn't filter, which it must do if the oil passes through it.
Now, if that's not what the author meant, he should find another line of work.

I know the what/why/how of bypass valves. I meant, if the media didn't actually filter the oil, there would be no need for one.

 

Maybe if he used the term screen, sieve, mesh, or strain, rather than "filter", it would have helped him make his point. I don't read into what he wrote about, that suggests that oil doesn't flow through the filter media, rather its how it flows & how that flow turbulence around the media fibers & through orifices between the fibers, that creates the centrifugal force that flings the particles out, rather than screening them out as the oil passes through the media, as most of us had probably envisioned.

 

I trust info right from the filter tech people more.
This is the reply I received to an email enquiry. (Relevant statement in bold)

Thank you for contacting Baldwin Filters with your inquiry. I have read the article and can see where some misinterpretation may be made based on how it is worded. Filtering, by definition is the removal of something from a fluid. Whether this is done via interception or absorption, it is still filtering. Particulate removal is done primarily through interception. A simple example of interception is filtering through a screen. Any particles larger than the openings in the screen will be filtered out( I believe this is the method, to which the article refers to as "Filtering". The media that is used in filtration today goes a bit further in particulate removal. Particles that are larger than the pores on the surface of the media are filtered out on the surface. However, as the fluid flows through the media it does have to change direction as it flows around the fibers that make up the media. This part of the filtration process enables the filter media to remove smaller particles, dependent on how tight the media fibers are woven together.

So, it does both. At least Baldwin does. Maybe Purolator does it different, but I doubt it.

 

Good idea to get another manufacturers input.
Yup, how the filter media works depends on what its made of. Paper media is usually thought of as a surface loading screening type, a fiber type media is uaually thought of as depth loading & usually filters to smaller particle sizes, while holding more of what it filters out, & of course a paper/fiber mix media is both surface & depth loading & it goes on & on. So, the filter design, media type, (medium to be filtered, liquid, solid, air), temp range, flow rate, pressure, filter service life, cost, etc, all dictate how the filter will be designed, what media will be used, how well it'll work, how long it'll last & how much it'll cost.

So, we users are tasked with finding the best filtering bang for the buck & sometimes that requires a little searching for the facts.

 

What You Need To Know About Engine Oil Filters More thoughts on filter media type, how it works & microscopic view of synthetic & cellulose fiber medias at 250X.

 

Where the heck do they find these people? Must be a buddy of the idiot who wrote the first one.
Then the stuff gets published on the internet and people take it as gospel.

 

Sometimes we have to look beyond a writers personal opinions & try to get our minds wrapped around the overall larger picture, of how different design filters & different filter media, or blends of filter media materials are likely to work in our application.

Seems to me what was being suggested, was that an inexpensive, poorly made, no-name filter, isn't likely to have quality components, nor have as much filter media, filter as well, nor last as long, as a better made more expensive filter by a known manufacturer, that has a reputation to up hold!!!

Certainly the OEM filters need to have a high probability of having the engine last as long as 8 years, for those with extended warranty, so that the extended warranty program will be a gravy train for the manufacturer, by not having many engine failures due to filter problems. SO, an OEM filter is likely to be a good bang for the buck to begin with, but if we want to try & find something a little better that's not OEM, for extended drains with the newer oils available, or we're using our vehicle in severe conditions, or we have an IOLM system, maybe the info in the articles can help us make a more informed filter decision.