Anyone change air filter every oil change? We are!

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Some good responses above. Richard Widmans's website contains very good information about the adverse affects of air filter cleaning as verified by real life results and oil analysis. Here are some SAE papers that verify dry air filter efficiency increase with use:
#680536 "Ingested Dust, Filters and Diesel Engine Wear"
#952557 "Total Filtration"
#2000-01-3317 "Service Life Expectations & Filtration Performance of Engine Air Cleaners"
2001-01-0307 "Discriminating Tests for Automotive Engine Air Filters"

Finally Do Not confuse air filter performance with oil filter performance. Oil filter efficiency does NOT improve with use. Maybe because the flow of fluid through a liquid filter media is laminar instead of turbulent with air. There are huge differences in density, viscosity, pressures and chemistry (dispersants) between air and various lubricants. Liquid filtration is much more complicated and depends upon many more variables. I am not sure that that advertised liquid filter tests duplicate field performance, but that is another subject.
 
The most important pieces of information in this thread (in no particular order) are;

Rear facing snorkel
Prefilter
Restriction gauge
Dnaldson Powercore.

Hello clean air!
 
"Oil filter efficiency does NOT improve with use."

Ahh do you have proof of that as I believe I have seen studies that say otherwise. I may have to do some digging.
 
Originally Posted By: philipp10
"Oil filter efficiency does NOT improve with use."

Ahh do you have proof of that as I believe I have seen studies that say otherwise. I may have to do some digging.


Here's a start:
Quote:
The multi-pass test bench (ISO 4548) is a standardized test for the filtration of hydraulic fluids and engine filters for oil and fuels. By using particle counters upstream and downstream of the filter, the filter efficiency can be determined in a detailed way. The quotient of captured over total particles is listed as a function of the particle diameter. During the test, the changes of the fractional efficiency over the life time can be observed.
It is usually assumed that fractional efficiencies increase over time: particles deposited in the filter block the pores progressively which results in a decrease in permeability. Thus one tends to conclude that fewer particles will be able to pass through the filter and the efficiency rises over time.
However, measurements performed on filter media sometimes contradict this assumption, as can be seen in Fig. 1. Here, we observe decreasing efficiencies over a long period of time. In fact, it decreases until the filter becomes complete clogged, at which point the efficiency sharply rises to 100%.

http://www.geodict.com/Publications/2013FiltechBeckerHahnLehmannWiegmann.pdf

Ed
 
Originally Posted By: philipp10
"Oil filter efficiency does NOT improve with use."

Ahh do you have proof of that as I believe I have seen studies that say otherwise. I may have to do some digging.


Ok Phillip, this is a good discussion although off topic. Check out the abstract and preview of following SAE papers:

#650865 "Oil Filtration and Lifter Wear"
#650866 "Filter Life vs Engine Wear"
#680258 "How to select Oil Filters"
#851590 "An Innovative Technique in Filter Rating"
#1985-02-01 "Engine oil Filter Performance with Synthetic and Mineral Oil"
#860735 "A Comparative Investigation of Filter Performance Under Laboratory and Field Conditions"
#860736 "Filter Performance with Cyclic Flow"
#860737 "The Influence of Surge Flow on Filter Performance"

Some of these are a little dated, but the principles should apply, even in hydraulic systems. It is obvious that the field performance of automotive oil filtration is not straight forward and deserves more scrutiny than the simple comparison of Beta ratios on a continuous short term test with fixed conditions using a non-additive hydraulic oil.

Easier to read articles are the following:
"Factors that Effect Oil Filtration" Noria Corporation no date noted.
"How Flow and Vibration Affect Filter Performance- Inside and Outside the Laboratory" Machinery Lubrication May 2003
"When is a Filter Not a Filter" Machinery Lubrication by Noria Corp. March 2009
"DFE-The Evolution in Filter Element Multi-pass Development Testing" HY-Pro Filtration Company

Quote from above "If we assume that a filter is like a black hole where all of the captured contaminant will remain trapped indefinitely we are operating with a false sense of security. If you are only discussing removal (capture) efficiency when it comes to filter elements you need to be looking at particle retention efficiency as well."

I would welcome input from those who really know filter performance to contribute here, especially how synthetic filter media compares to cellulose media, but this really needs to be in the oil filter topic.
 
Originally Posted By: compratio10_5
Originally Posted By: philipp10
"Oil filter efficiency does NOT improve with use."

Ahh do you have proof of that as I believe I have seen studies that say otherwise. I may have to do some digging.


Ok Phillip, this is a good discussion although off topic. Check out the abstract and preview of following SAE papers:

#650865 "Oil Filtration and Lifter Wear"
#650866 "Filter Life vs Engine Wear"
#680258 "How to select Oil Filters"
#851590 "An Innovative Technique in Filter Rating"
#1985-02-01 "Engine oil Filter Performance with Synthetic and Mineral Oil"
#860735 "A Comparative Investigation of Filter Performance Under Laboratory and Field Conditions"
#860736 "Filter Performance with Cyclic Flow"
#860737 "The Influence of Surge Flow on Filter Performance"

Some of these are a little dated, but the principles should apply, even in hydraulic systems. It is obvious that the field performance of automotive oil filtration is not straight forward and deserves more scrutiny than the simple comparison of Beta ratios on a continuous short term test with fixed conditions using a non-additive hydraulic oil.

Easier to read articles are the following:
"Factors that Effect Oil Filtration" Noria Corporation no date noted.
"How Flow and Vibration Affect Filter Performance- Inside and Outside the Laboratory" Machinery Lubrication May 2003
"When is a Filter Not a Filter" Machinery Lubrication by Noria Corp. March 2009
"DFE-The Evolution in Filter Element Multi-pass Development Testing" HY-Pro Filtration Company

Quote from above "If we assume that a filter is like a black hole where all of the captured contaminant will remain trapped indefinitely we are operating with a false sense of security. If you are only discussing removal (capture) efficiency when it comes to filter elements you need to be looking at particle retention efficiency as well."

I would welcome input from those who really know filter performance to contribute here, especially how synthetic filter media compares to cellulose media, but this really needs to be in the oil filter topic.


I don't have a clue how to get access to these papers. Do I have to pay?
 
Originally Posted By: edhackett
Here's a start:

Thanks for that, Ed. I may have to take some time and go through it.

By the way:

Quote:
As we have seen in Section C, a single huge pore has a drastic effect on the overall efficiency, as it will collect all the flow once the smaller pores are clogged.

Does that apply to media tears as well? With this being coauthored by people from Mann+Hummel, it is a bit ironic.
whistle.gif
 
Phillip, here is how to access the preview of Society of Automotive Engineers technical papers. Google SAE technical papers. Type the paper number or key word into the search bar in the upper right hand of the screen and click Q. When the paper(s)title come up click on the title and read the abstract, If you want to see more click on the preview bar on the right side of the screen. You can learn a lot just by reading. If you want more, you will have to pay for it or access it through a University that subscribes to SAE.
 
Originally Posted By: edhackett
Originally Posted By: philipp10
"Oil filter efficiency does NOT improve with use."

Ahh do you have proof of that as I believe I have seen studies that say otherwise. I may have to do some digging.


Here's a start:
Quote:
The multi-pass test bench (ISO 4548) is a standardized test for the filtration of hydraulic fluids and engine filters for oil and fuels. By using particle counters upstream and downstream of the filter, the filter efficiency can be determined in a detailed way. The quotient of captured over total particles is listed as a function of the particle diameter. During the test, the changes of the fractional efficiency over the life time can be observed.
It is usually assumed that fractional efficiencies increase over time: particles deposited in the filter block the pores progressively which results in a decrease in permeability. Thus one tends to conclude that fewer particles will be able to pass through the filter and the efficiency rises over time.
However, measurements performed on filter media sometimes contradict this assumption, as can be seen in Fig. 1. Here, we observe decreasing efficiencies over a long period of time. In fact, it decreases until the filter becomes complete clogged, at which point the efficiency sharply rises to 100%.

http://www.geodict.com/Publications/2013FiltechBeckerHahnLehmannWiegmann.pdf

Ed

Interesting Ed. It runs counter to information provided by the lead Fram engineer I spoke with some years ago at their labs. Basically suggested the 1 year 12k mi box recommendation was more/most about selling filters.

It also runs counter to what Jim Allen had long posted about air filter intervals and use. His thoughts are documented in the now classic (imo) bitog air filter thread started by member JOD, linked. His first post there is representative. https://bobistheoilguy.com/forums/ubbthreads.php/topics/4348255/1
 
Originally Posted By: Chris142
Put a filter restriction gauge on it. You may be replacing them for no reason.


+1 This way you can change it when there is true restriction. Even though it looks pretty dirty it might have some life left in it. Help you save some scratch
 
This is a reply to Sayjac, I believe that you are confusing the discussion between air filters and oil filters. Many on this board seem to think that both type of filters age the same. They do not. Dry air filter efficiency improves with use as a dust cake is established which removes smaller particles. Oil filter efficiency gets worse with use as motor oil dispersants prevent cake formation and the smaller particles migrate through the filter during cyclic changes in flow rate and viscosity. Ed is replying to a question about OIL filter efficiency.
 
^^^^Ok got it now. It's what happens when one, in this case me, assumes something. As this is the AF board I assumed that was the reference without thoroughly reading. Ugh. But good to know the Jim Allen and the Fram engineer were on target.

Still interesting about the OF as one my first posts after I joined was a discussion about OFs becoming more efficient with use. As the abstract is a 2013 paper, relatively new-ish.

That would shoot down the idea some have why the Asian Oem filters (based on Amsoil data) can be relatively inefficient and in the case of the Honda oem why they recommend an every other oci filter change. But that's another topic.
 
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