Will a well maintained engine have smaller sized contaminants?

[The motor guy]

Let's say the filter filters 99% at 30 microns. How many particles will actually reach that size before getting caught by the filter? I'd imagine if an oil filter catches 99 percent at 30 microns, then it should catch half of that at 15 microns and most will probably be caught before even reaching the full 30 microns, correct?

 

[Oillover]

sometimes they do

 

[Lubener]

Filtering efficiency increases as the filter loads up with contaiminants up to a point before bypassing takes place.

 

[ZeeOSix]

Filtering efficiency increases as the filter loads up with contaiminants up to a point before bypassing takes place.

Oil filters actually lose efficiency as they load up. It's a long running misconception that they get more efficient. Ascent's ISO 4518-12 testing showed that on all the filters he treated. Air filters can get more efficient with loading, but not oil filters.

 

[ZeeOSix]

Let's say the filter filters 99% at 30 microns. How many particles will actually reach that size before getting caught by the filter? I'd imagine if an oil filter catches 99 percent at 30 microns, then it should catch half of that at 15 microns and most will probably be caught before even reaching the full 30 microns, correct?

Every oil filter has an "Efficiency vs Particle Size" performance curve. Like these.

U

Post in thread 'Would you all like to see ISO 4548-12 Oil Filter Lab Testing Comparison, Efficiency & Capacity, Pressure vs Flow, Bubble Point, and Burst?'

Jun 4, 2021

I will get a video out with more details, but at the moment I cannot. I hope you all enjoy this summery of your favorite filters! You all have waited long enough and I appreciate you patients!

• UNC034

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[dnewton3]

The answer to the question about how a well-maintained engine is protected from particle size is not a one-size-fits-all answer ... The primary misunderstanding is how particles enter and exist in the lube system, and what constitutes their makeup.

By far, the most damaging particles are soot and silica; these are very hard and abrasive. The other particles to discuss are typically metals. Soft metals (Pb, Cu, Al) are typically shed into the lube at fairly low rates; low enough to not be of major concern. Hard metals (Fe, Cr) can be present in varying amounts; Fe typically rises in quantity relative to fuel burned and OCI duration, whereas Cr is typically just low-wear in quantity in a healthy engine. The metals are typically reactive; they don't exist in any dangerous size or quantity until wear puts them into circulation.

Some contamination comes in via the air intake tract. Silica, mainly. These don't change size. A good air filter, left in place, can help reduce the presence of these in the lube sump. What's not caught by the air filter, can be caught by the lube filter if they are large enough.

Soot, OTOH, originates from incomplete combustion of the hydrocarbon fuel source. It starts out small; very, very small. Soot starts out (as a generalization) around 40nm in size; give or take a bit. That's nanometers, not micrometers. Soot amalgamates (co-joins) with other soot particles to become bigger. A typical soot particles has to grow 100x larger just to become 4um; and at that size it would still be too small to be caught by a typical FF filter. The size of soot is primarily not controlled by the FF filter; it can only remove them after they get really large (10um are larger for any reasonable efficiency effect). Rather, it's the anti-agglomerate additive in the oil that helps keep the soot small enough to not be of major concern. The DI (dispersant/inhibitor) additives are there to reduce the growth rate of soot, giving longer OCI protections. The more of the additives, the longer the OCI can be safely maintained. I have often argued that the oil additives are in control of wear rates far more than a lube filter, because the filter can only react to soot particle size after the oil fails to control it. Conceptually, the thing to understand about soot is that quantity and size are related, but not mutually assured. Having 3% of soot in a system doesn't tell you anything about size; no UOA can tell you the size of a soot particle, other than it's small enough to be vaporized in the plasma stream of the test (typically below 5um).


The following factors play into wear control, as a team of contributors:
- oil change interval
- oil additive package strength
- lube filter efficiency
- lube filter change interval
- air filter efficiency
- air filter change interval
- engine combustion efficiency
Managing wear is about controlling the contributing factors as inputs, with wear rates being the output.

 

[ZeeOSix]

A good air filter, left in place, can help reduce the presence of these in the lube sump. What's not caught by the air filter, can be caught by the lube filter if they are large enough.

Yep, as said many times the oil filter (beside dumping the oil) is the only thing in the system left to keep the oil clean once debris gets in the oil from whatever source. The longer the OCI, the more a higher efficiency filter benefits keeping the oil cleaner and therefore the wear rate down. Not a good idea to run an oil filter that's 50% @ 20u for a 10K-15K OCI.

Particles below 20u actually cause the most wear (every wear study shows that), so using an oil filter that is higher efficiency is going to catch more particles below 20u than a much less efficient oil filter - see post 5 graphs. Wear rate due to debris caught between two moving and rubbing parts is proportional to the level of contamination in the oil and the OCI. The longer the OCI, the more the debris level increases and the more times the sump is circulated through the oiling system. Increase those factors and you increase wear from debris. As discussed in some other threads, magnets used to capture ferrous debris the oil filter can't catch can also help reduce the wear rate. Any debris you can prevent from being recirculated through the engine over and over is beneficial.

 

[Hohn]

Air filters can get more efficient with loading, but not oil filters.

Yes! Inscribe this on stone tablets!

Air filters will usually get into "cake filtering" when a layer of dust accumulates, and the surface dust almost acts like an ultrafine pre-filter. Air filters get more restrictive *and* more efficient as they load.

Oil filters are depth media. As oil filters load they get more restrictive and less efficient. This has to do with changes to the effective pore sizes as the filters load, but also the higher face velocity that results from less flow area.

It's common to think of filters is filtering only by blocking particles within the pores, but in reality with depth-style media, a lot of the particles are caught by just sticking to the fibers, like flypaper. The higher the velocity, the less likely it will stick. Is the filters load, it's like the flypaper has no more sticky surfaces and the particles in the fluid are flying past too quickly to stick anyway.

 

[CarlB]

Oil filters actually lose efficiency as they load up. It's a long running misconception that they get more efficient. Ascent's ISO 4518-12 testing showed that on all the filters he treated. Air filters can get more efficient with loading, but not oil filters.

Does the Ascent study actually invalidate the SAE papers?

 

[Hohn]

Let's say the filter filters 99% at 30 microns. How many particles will actually reach that size before getting caught by the filter? I'd imagine if an oil filter catches 99 percent at 30 microns, then it should catch half of that at 15 microns and most will probably be caught before even reaching the full 30 microns, correct?

That's not how the efficiency curves work. They can vary wildly depending on media design. You might find that the efficiency can gain or lose orders of magnitude in just a couple microns, or that the curves are quite flat until they hit a sudden "knee" and shift radically.

As an example, one fuel filter I work with has a beta ratio of 1000 at 7 microns. But it's only 100 at 6 microns. And it's well under 30 at 4 microns. What's the beta ratio at 14 microns? About 10^21.

Or consider a really simple example like the Baldwin 7318. It's nominally rated at 9.8 microns, that's a 50% efficiency or coin toss odds. The "absolute" rating -typically 98.7%--is 27 microns.

Unfortunately, the shape of the efficiency curves below their rated particle cutoff is just a guess. But in general, synthetic media will have the sharpest cutoffs, followed by blend, followed by cellulose.

This is why a cellulose media filter like the B7318 has a pretty "soft" curve where the efficiency falls by only 48.7% as you go from 27 microns to 9.8-call-it-10 microns. Synthetic media has much steeper curves owing to the much more uniform pore sizes and smaller fibers. While this causes efficiency to drop off much faster below the rated micron size, it also means the efficiency rises very fast above it.

This is a big reason why synthetic media can not only offer superb protection (rated particles and larger) but also do it for a long, long time (not plugging with smaller particles).

 

[ZeeOSix]

Does the Ascent study actually invalidate the SAE papers?

What SAE papers ... got some links? I'd like to read what those papers say.

Purolator/Mann+Hummel said the same thing many years ago - their paper snip about it shown below. This has been discussed in many threads here over the last 5+ years. This is the same thing that Ascent saw in his official ISO test data.

 

[ZeeOSix]

Here's where the decrease in efficiency data is shown for the filters that Ascent tested.

D

Post in thread 'Would you all like to see ISO 4548-12 Oil Filter Lab Testing Comparison, Efficiency & Capacity, Pressure vs Flow, Bubble Point, and Burst?'

Jun 4, 2021

Interestin

Yes, a pre Determined DeltaP determines the end of the test. In our case I choose 8PSID over clean assembly. For the ISO 4548-12 multipass test the average of readings taken every X seconds over a 5 min or 10 min time interval are averaged and reported depending on how long the test takes to reach that Terminal DeltaP.

What you see here in the previous graphs is an average taken from each time interval reading the entire time of the test and averaged. You can look at each time interval and see how it changes over time.
Here is an example of the AC-Delco time interval report...

• Davejam

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[CarlB]

What SAE papers ... got some links? I'd like to read what those papers say.

Purolator/Mann+Hummel said the same thing many years ago - their paper snip about it shown below. This has been discussed in many threads here over the last 5+ years. This is the same thing that Ascent saw in his official ISO test data.

View attachment 307923

I believe 930017 is the one that gets referenced. I've not seen a free download for it.

 

[ZeeOSix]

I believe 930017 is the one that gets referenced. I've not seen a free download for it.

The SAE paper summary doesn't mention anything about it ... mainly talking about how better filtration reduced engine wear (no surprise there). Maybe they were talking about how the oil filter will suddenly increase in efficiency about when it's totally clogged as the graph above shows. But that's not really what you want to do with an oil filter unless you want it to go into bypass at that level of clogging.

https://www.sae.org/papers/optimizing-lubricating-oil-filtration-systems-diesel-engines-930017

 

[gfh77665]

Air filters can get more efficient with loading, but not oil filters.

That's interesting.

 

[The motor guy]

Are they testing the filter or just the media? I wonder if they account for the fram leakage

 

[ZeeOSix]

Are they testing the filter or just the media? I wonder if they account for the fram leakage

Probably not tested on a filter with an internal leak. Besides, Purolators don't use a leaf spring to end cap seal configuration. The Purolator data could have been on just the media. Ascent saw the decrease in efficiency on all the filters he tested as they loaded up with debris. Not all of them had a leaf spring to end cap seal.

A internal leak is going to cut the efficiency down right from the start. Larger the internal leak, the larger the reduction in efficiency regardless of how the media performs.