Another Soapbox Rant

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Sep 18, 2002
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VA
With all respect to all who read this, I am simply asking a question. Most of you know my penchant for OEM parts (my definition of OEM is "items purchased from a legit auto dealer") so please try and forget that for now.

When you are replacing maintenance parts, say air filters, how can you visually inspect an air filter and say it is just as good or better than an OEM?

On RA, there are 13 different choices for my 4Runner ranging from $2.86 to $15.58. There are 12 choices for my GX ranging from $3.60 to $17.10.
They can't all be the same, can they? Before my OEM days, I had purchased many parts from many places and all the air filters I purchased
looked about the same. Some had stiffer filter material, some had fluffier material, some had different color frames, etc. I even used one of those
oiled filters til I saw my throttle body and MAF sensor coated in oil.

How do we judge air filters? How do we know which one is better for our vehicles?
How can we look at metal and rubber components on our parts and determine this metal is better than that? Or just as good as?

Every HVAC guy that comes to my house tells me to use those cheap $1 filters in my furnace. Seriously, I just can't do it.

Maybe this is just a rant....Maybe in the real life world we live in, there are no "correct" answers.
 
I like power so I run low efficiency filters. Cheap STP.

On the Nissan and the Subaru I've found the high efficient filters REALLY throttle the engine back.

I noticed that by doing back to back WOT runs ( after I installed a new filter and power was WAY down).
_____________________

I would just go by what the reputable filter manufacturer state in thier marketing material.

___________

If In your house, tables and horizontal surfaces require dusting to frequently, go a step up.

BUT! You want to keep the efficiency of the FILTER as low as you can
to keep the HVAC CFM as high as it can be.

Like your HVAC guy said.

- Ken
 
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I used to buy OEM parts above everything else, and I still do in some cases, but my new philosophy is "buy what is the best quality for the price". In some cases OEM is better (like sensors), but they use suppliers, and things like Mopar oil filters are made by Purolator, so an aftermarket like a Fram Ultra is a better made filter for the price. When it comes down to it, you just have to do your research on products. When buying parts on RA I've never seen in person, I tend to stick with the "better" or "heavy duty" version of whatever it is. Obviously the $3 filter is likely to be cheaper made than the $15 one, but I also find with RockAuto that sometimes the most expensive brands aren't worth the money. The $15 filter might not be any better than the mid-range $8 filter.

As for air filters/oil filters, I try to buy brands that I know will have quality. For air filters: Wix, Fram, Mann, etc. Buy the mid-grade product, or a product listed somewhere near the top of their category, and move on with life. I avoid cheap parts, but I also don't stress about an $8 filter vs. a $12 filter. Reality is that since we are BITOG'ers, we take care of our vehicles, and they will likely meet their demise from being hit by someone else or other outside factors than engine problems or neglect.
 
Well you don't know just like you don't know that a specific genuine part from the dealer is guaranteed to meet the requirements of the automaker. It's an assumption. In fact what you're buying with a dealer part is a higher probability that it fits and performs as required by the automaker.
 
All items will have variability. Unless stringently specified and held to a license there's always a question. For filters, its pleats, media quality/efficiency, and to some extent seal selection will be differences. The reality is, how much does it matter, within reason? Maybe not that much. Maybe some. Maybe there's a difference betwen lasting 185k miles and 200k miles.

Metallurgy is a bigger challenge. "Made to" designs which copy original parts is another big challenge. Sometimes aftermarket parts have improvements. Usually theyre about the same or maybe pulled a bit of cost out of them.

OP, your HVAC guy probably has one of two opinions:
1) something in there is better than nothing or an old dirty one
2) performance is better with higher flow, lower filtration filters

If the evaporator can be readily accessed and cleaned, Id see no reason to use anything but the cheaper filters, assuming that youre not seeing excessive dust in the ducts and in the house, and allergies arent an issue.
 
Plus, Gebo, your's wasn't a rant as much as it was a question. A well fleshed out question at that.

Is weight a usable comparison criteria for filters?

My first Hastings oil filter; an old style 115A (a hugey used in Ford V8's) for my '77 Celica was heavier than others by far.
That baby had a sheet metal removal nut welded on.

Maybe weighing air filters is one data point to throw into the mix.
 
Originally Posted by Gebo


When you are replacing maintenance parts, say air filters, how can you visually inspect an air filter and say it is just as good or better than an OEM?

How do we judge air filters? How do we know which one is better for our vehicles?
How can we look at metal and rubber components on our parts and determine this metal is better than that? Or just as good as?

Every HVAC guy that comes to my house tells me to use those cheap $1 filters in my furnace. Seriously, I just can't do it.

Maybe this is just a rant....Maybe in the real life world we live in, there are no "correct" answers.


Listen to an engineer who specializes in all types of filtration and has had input in many of these much "vaunted" ISO standards and other tests. I'll tell you the simple facts as I don't have a dog in the "best air filter" fight and will leave the bickering arguing specifications they don't fully comprehend ( especially the purpose, weaknesses, limitations and conditions) and a science they don't understand to any significant degree.

Listen to your HVAC guy, he is correct for 99% of all applications.

You (the individual) cant "look" at anything other than an obvious defect in manufacturing. Engineering analysis of filters requires lots of equipment and careful controls to get the right answers to the right questions.

Then what's right "for you" is another level of qualifier and highly conditional.

So, as a guideline for selection, here is what you need to do ( without investing tons of time and money in testing) Everything is a partial trade off with benefits and liabilities.

1- decide what performance characteristics mean most ( and least) to you in terms of aspiration performance. (HP, cleaner air, whatever)

2- decide what level of benefit ( or liability) you are willing to accept? ( is that little extra silica in size and volume really damaging my engine with my oil selection and change frequency?)

3- go with it and ignore all the controversy argued by the masses.

4- don't be afraid to experiment as new things come along.

Now if you have a high degree of knowledge of the science of filtration, engineering & design and a fully equipped lab at your disposal, contact me and I may have some projects for you but for the average guy, that's the best route.

There are too many areas of a filter (internal and external to the filter) and the specific filtration process that have to be considered and analyzed certain ways under certain conditions for this to be generic. Its a very involved science and field.
 
Originally Posted by Kira


Is weight a usable comparison criteria for filters?

Maybe weighing air filters is one data point to throw into the mix.


Actually, in the actual field- its the most important test because it tells you retention as a volume under actual conditions in a given time or circumstance ( we did that a lot after sandstorms in Afghanistan and Iraq determining PM frequencies and analysis on vehicles on march and generators)

Then sending it off will tell me things like particle size, distribution, efficiency deviation and so forth.

On a regular auto filter, that may not give much useful data as I would imagine it would be a fraction of a gram but worth a shot.
 
Originally Posted by ARCOgraphite
I like power so I run low efficiency filters. Cheap STP.

On the Nissan and the Subaru I've found the high efficient filters REALLY throttle the engine back.

I noticed that by doing back to back WOT runs ( after I installed a new filter and power was WAY down).
_____________________

I would just go by what the reputable filter manufacturer state in thier marketing material.

___________

If In your house, tables and horizontal surfaces require dusting to frequently, go a step up.

BUT! You want to keep the efficiency of the FILTER as low as you can
to keep the HVAC CFM as high as it can be.

Like your HVAC guy said.

- Ken




I like how you mentioned the dust accumulation in a house. Makes good sense. Gonna do an experiment.
 
Let me clarify my "rant." I'm not questioning anyone's parts. I'm not saying one is better than the other.


I'm just wondering how do WE know what we are buying? For the most part, we just
have to trust the mfr is manufacturing a "quality" part. On the other hand, a well trained
mechanic may see certain items fail more frequently than we do and have greater insight
as to the quality but we (I am in the "we") make our decisions on price, weight, feel, looks,
he said, bitog forum, YouTube, Daddy says, etc.

Do we really know what we are buying? I guess in the grand scheme of things as long as
we are comfortable with our decisions, it probably ain't gonna matter a whole lot.
 
For air filters in particular, there was a good Project Farm YouTube video a couple months ago where he did some very interesting testing.
 
Originally Posted by Gebo
Let me clarify my "rant." I'm not questioning anyone's parts. I'm not saying one is better than the other.


I'm just wondering how do WE know what we are buying? For the most part, we just
have to trust the mfr is manufacturing a "quality" part. On the other hand, a well trained
mechanic may see certain items fail more frequently than we do and have greater insight
as to the quality but we (I am in the "we") make our decisions on price, weight, feel, looks,
he said, bitog forum, YouTube, Daddy says, etc.

Do we really know what we are buying? I guess in the grand scheme of things as long as
we are comfortable with our decisions, it probably ain't gonna matter a whole lot.


You have a truly relevant and wholly legitimate question that deserves a direct answer but that answer is elusive because its conditional, has "degrees of correctness" and the standards ( even when followed diligently) are based on standardized laboratory tests that are ONLY APPLICABLE if your specific application falls within the test parameter.

I catch it from both sides and the most ornery are those who spout ISO and all that as if the result actually means something just because its a "target to be met" that some process engineer can check off ( which it does and in terms of a standard test all competing items can be measured against, it works great) HOWEVER, that ISO test may NOT be relevant to the situation you brought us to resolve so then come custom tests. Many times those will contradict the ISO versions and findings but that's normal and expected when you are testing specific products against specific conditions.

That's why your mechanic ( assuming he is qualified, vendor neutral and motivated to give you the best service possible) and his recommendation should be considered as high or higher than all the market claims. ( and get a 2nd opinion)
 
Originally Posted by AJB0009
For air filters in particular, there was a good Project Farm YouTube video a couple months ago where he did some very interesting testing.


Not the word I would use, much closer to misleading and close to dancing around fundamentally and fatally flawed at every level.
 
Most OEM filters work fine, but most OEM oil filters don't usually live in the upper efficiency scale than many aftermarket oil filters (as an example). I buy oil and air filters based on their respective ISO efficiency test ratings, and the air filters need to have an ISO efficiency with a fine dust test spec.

Beware of parts on RockAuto ... can be hit or miss.

Originally Posted by Gebo
Every HVAC guy that comes to my house tells me to use those cheap $1 filters in my furnace. Seriously, I just can't do it.


I run furnace filters that are around MERV 10 which is about 3/4 up the furnace filter efficiency scale. Change it once a year and have never had any issues for 20+ years.
 
Originally Posted by ABN_CBT_ENGR
Originally Posted by Gebo
Let me clarify my "rant." I'm not questioning anyone's parts. I'm not saying one is better than the other.


I'm just wondering how do WE know what we are buying? For the most part, we just
have to trust the mfr is manufacturing a "quality" part. On the other hand, a well trained
mechanic may see certain items fail more frequently than we do and have greater insight
as to the quality but we (I am in the "we") make our decisions on price, weight, feel, looks,
he said, bitog forum, YouTube, Daddy says, etc.

Do we really know what we are buying? I guess in the grand scheme of things as long as
we are comfortable with our decisions, it probably ain't gonna matter a whole lot.


You have a truly relevant and wholly legitimate question that deserves a direct answer but that answer is elusive because its conditional, has "degrees of correctness" and the standards ( even when followed diligently) are based on standardized laboratory tests that are ONLY APPLICABLE if your specific application falls within the test parameter.

I catch it from both sides and the most ornery are those who spout ISO and all that as if the result actually means something just because its a "target to be met" that some process engineer can check off ( which it does and in terms of a standard test all competing items can be measured against, it works great) HOWEVER, that ISO test may NOT be relevant to the situation you brought us to resolve so then come custom tests. Many times those will contradict the ISO versions and findings but that's normal and expected when you are testing specific products against specific conditions.

That's why your mechanic ( assuming he is qualified, vendor neutral and motivated to give you the best service possible) and his recommendation should be considered as high or higher than all the market claims. ( and get a 2nd opinion)



Very, very good post as usual ^^^^^^^^

In say a air filter would it be correct to first define what size particles are the most damaging ??

Say 10-20 microns in size.

Once one has the answer to that question then would it not be good to have a efficiency/efficacy goal for particles of that size ?

Say 98-99.5 percent.

And finding a air filter that comes as close as possible to actually meeting those desired goals and or expected efficiency/efficacy per a ISO fine dust testing.

Maybe ISO fine dust testing is not exactly like real world conditions... But what else could one go by?

Just wondering what would be "best" practice...
 
Originally Posted by bbhero


Very, very good post as usual ^^^^^^^^

In say a air filter would it be correct to first define what size particles are the most damaging ??

Say 10-20 microns in size.

Once one has the answer to that question then would it not be good to have a efficiency/efficacy goal for particles of that size ?

Say 98-99.5 percent.

And finding a air filter that comes as close as possible to actually meeting those desired goals and or expected efficiency/efficacy per a ISO fine dust testing.

Maybe ISO fine dust testing is not exactly like real world conditions... But what else could one go by?

Just wondering what would be "best" practice...


Well, here's the problem. That efficiency number is all but meaningless outside of a lab and you will never know if you hit it.

In order for that to make sense, one has to understand how an air filter works then the truth will become obvious.
ALL (yes all membrane filters) employ 2 different methods to achieve filtration. Some difference in flow dynamics between air and oil but the principle is basically the same.

Direct and indirect interception

Direct is simple- a hard sieve or screen, nothing bigger than the hole will pass. They tend to clog and lose flow real fast but they are the ultimate method.
Indirect is the pleated types because they do several things

The housings create a turbulent cyclonic environment where the air velocity and particle velocity start to decouple. (Just like a cyclone scrubber principle).

The slower particles now impact the pleated media at oblique angles losing inertia and acceleration. (Similar to a round striking sloped armor on a tank)

They start "meandering" within the weave and eventually stick because unlike test silica they are all kinds of shapes and abrasive grabbing characteristics.

Eventually they get caught in the spider web and start to accumulate. (Bed) that's why filters get better with age.

Then it's a matter of surface area and capillary action between the air outside versus what's needed on the inside as to whether it filters enough to operate properly. ( needs replacement)

All membrane filters have all of that in varying degrees ( with varying results obviously)

Then are the add-ons like oil impregnation, swelling/flexing media and all that.

So, in the real world you cannot know the size, weight, geometry, moisture saturation or particle size distribution of the dust you are sucking in so you cannot even begin to calculate filter efficiency.

So for a field expedient best practice that achieves basic goals with a minimum risk , I recommend getting a filter that gives you the pick up and HP you want and periodically sample oil for contamination and inspect engine for particulate induced damage and if you don't see any- carry on.

If you do, determine the source and address it.

Then sit back and watch people argue numbers they don't understand and how they interact in a science that's beyond them in ways they will never know.
 
Well I guess what I have done so far has been all right...

lol.gif


No noticeable loss of power from my VQ engine and no leaks either at 307,300 miles...

It makes sense what you said about the air filter housing unit... And how a typical pleated air filter works more via the indirect way.

Of course the air filter fitting correctly with a tight seal is of high importance has well.
 
Originally Posted by bbhero
Well I guess what I have done so far has been all right...

lol.gif


No noticeable loss of power from my VQ engine and no leaks either at 307,300 miles...

It makes sense what you said about the air filter housing unit... And how a typical pleated air filter works more via the indirect way.

Of course the air filter fitting correctly with a tight seal is of high importance has well.


I'm sure of it ( yeah a good fit & seal helps quite a bit too)

All manufacturers try to find the balance for their product.

The ISO tests are excellent from the perspective of a hard standard to compare like items horizontally and vertically on specific parameters and are very valuable in that regard.

But as an indicator of actual performance under real world conditions- they are not only useless, they can be damaging because the tests don't cover all real world scenarios and those standards are only valid within the ranges set.

Gives a lot of people a false sense of confidence.

My preference is membrane types rather than perf paper because they flex and trap more per surface area and still allow for good flow in all ranges because of the flexing except when dumped on. The more they bed, the finer they filter too. Just always get the highest surface area you can get in the housing. Not perfect but very adequate.
 
What would be an example of a membrane type air filter ??

For a car or truck ??

Closet one I can think of maybe a Powercore air filter...
 
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