I've been on this site for quite a while, and I've seen this topic brought up from time to time but I haven't been able to find conclusive evidence. It's been a while since this was discussed (that I noticed) so I thought I'd bring this up again.
What micron rating has been shown to cause the most damage? I've seen conflicting information on this topic, some sources state that anything under 2 microns are too small to cause any damage as most clearances are larger than 2 microns. Other sources note that 2-10 microns are the damage causing particles, while others state damage occurs with particles up to 20 microns.
I started looking into this because I noticed a decent amount of variance among filter manufacturers and their efficiency (not nominal) ratings. I'll use the following as an example as they all have a similar price point.
PureOne 14612 ($5.75) - 99.9% @ 40um ISO 4548-12
EcoGard S4612 ($5.31) - 99.9% @ 30um ISO 4548-12
Fram TG6607($6.69) - 99% @ >20um ISO 4548-12 based on average of TG8A, 3387A, & 4967
Microns. What's most damage inducing?
- Thread starter RamFan
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25.4 microns = .001 inch
I believe that the <20 micron cause the most wear (I believe there have been SAE studies on this - e.g. http://www.upmpg.com/tech_articles/sae_filtration_study/index.html); however it is also my understanding that this wear is dwarfed by cold-startup wear in the average gasoline automobile. The more highway miles driven (and the fewer startups) means the particulate wear becomes more of an issue.
Originally Posted By: RamFan
I started looking into this because I noticed a decent amount of variance among filter manufacturers and their efficiency (not nominal) ratings. I'll use the following as an example as they all have a similar price point.
PureOne 14612 ($5.75) - 99.9% @ 40um ISO 4548-12
EcoGard S4612 ($5.31) - 99.9% @ 30um ISO 4548-12
Fram TG6607($6.69) - 99% @ >20um ISO 4548-12 based on average of TG8A, 3387A, & 4967
I would't worry so much.
I'm no tribologist but I'm not sure you can answer your question in the way it's asked. The type of contact is what determines abrasive wear...and if there are soft and hard particles in that same micron size doing different things then a demarcation line of 20 or 40 microns probably doesn't give you an accurate portrayal. If some particulate has more eroding or etching properties than others over a 20-40 micron range then I would think it's more about the type of particulate than the micron size x however many miles. Old oil versus new oil...or that guy on here that says the best oil filter is a good air filter.
I believe that's why they use constant and relational algorithms to closer determine both the size and type of particles in analyzing wear. It's not so much a one dimensional question.
Originally Posted By: Jonzobot
I believe that the <20 micron cause the most wear (I believe there have been SAE studies on this - e.g. http://www.upmpg.com/tech_articles/sae_filtration_study/index.html); however it is also my understanding that this wear is dwarfed by cold-startup wear in the average gasoline automobile. The more highway miles driven (and the fewer startups) means the particulate wear becomes more of an issue.
Think of it this way, what happens in the lab stays in the lab. Normal or severe operating conditions will never replicate lab conditions.
Motorking said in a video somewhere that 10-20 microns is the most damaging range. I can't seem to find which video it is, though 
To add ... engines under heavy and sustained loads can cause more engine wear, especially in the rod and crank journal bearings because of higher oil temperatures, and therefore a resulting lower MOFT between the parts. Get an oil cooler if heavy towing loads are something your vehicle experiences on a regular basis.
If you are happy with 200k miles of engine service, change the oil at the manufacturers intervals with the manufacturers suggested oil and filter. Any engine failure will not be particulate wear related.
If your looking for a 1million mile car. Thats different but a few toyota hold that title with no special filter or oil.
My cars at least 10 or so have regularly run over 150k before being sold in fine running condition.
All of this banter on optimizing oil and filterperformance is mainly for fun not necessity.
Originally Posted By: slacktide_bitog
Motorking said in a video somewhere that 10-20 microns is the most damaging range. I can't seem to find which video it is, though
The story is its particles with similar dimensions to the operating clearances.
This implies there's effectively no lower cutoff (or if there is its less than a micron), since some parts (rings, cams) are in sliding contact at least some of the time.
This perhaps further implies that the smallest particles are the most damaging, since these are the most numerous.
Particles that are larger than the operating clearances are supposed to be relatively harmless, since they aren't supposed to enter between the moving surfaces. Given the "wedge" shape of the bearing/cam interface example usually used I find this a bit counter-intuitive, but that's the story. Probably doesn't matter too much there anyway since the larger particles are a lot less numerous.
The implication of all this seems to be that standard oil filtration, which mostly removes particles at the upper end (say around 20 mu) of the range, is fairly innefective in reducing wear.
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SAE Testing
In the 1988 Correlating Lube Oil Filtration Efficiencies
With Engine Wear technical paper published
by the Society of Automotive Engineers
(SAE), the relationship between filtration levels
and abrasive engine wear was established. Testing
determined that wear was reduced by as much as
70 percent by switching from a 40µ filter to a 15µ
filter.
The SAE conducted tests on a heavy-duty diesel
engine and an automotive gasoline engine, and
both provided consistent results.
Here is an informative link on filters -
https://www.amsoil.com/techservicesbulle...gine%20Wear.pdf
Originally Posted By: shanneba
SAE Testing
In the 1988 Correlating Lube Oil Filtration Efficiencies
With Engine Wear technical paper published
by the Society of Automotive Engineers
(SAE), the relationship between filtration levels
and abrasive engine wear was established. Testing
determined that wear was reduced by as much as
70 percent by switching from a 40µ filter to a 15µ
filter.
The SAE conducted tests on a heavy-duty diesel
engine and an automotive gasoline engine, and
both provided consistent results.
Here is an informative link on filters -
https://www.amsoil.com/techservicesbulle...gine%20Wear.pdf
Originally Posted By: shanneba
SAE Testing
In the 1988 Correlating Lube Oil Filtration Efficiencies
With Engine Wear technical paper published
by the Society of Automotive Engineers
(SAE), the relationship between filtration levels
and abrasive engine wear was established. Testing
determined that wear was reduced by as much as
70 percent by switching from a 40µ filter to a 15µ
filter.
The SAE conducted tests on a heavy-duty diesel
engine and an automotive gasoline engine, and
both provided consistent results.
Here is an informative link on filters -
https://www.amsoil.com/techservicesbulle...gine%20Wear.pdf
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