5 minute lesson on air filters please

[electrolover]

So I can honestly say I have never opened this section. Anyone got time for a quick lesson on air filters? If you had to rate them in order of efficiency and quality what would that order be?

I usually just buy wix or napa gold but its about time to change both of them so it got me thinking on the subject...

 

[gfh77665]

Don't over think it. Just buy a reasonably well made filter, Wix, CarQuest, NAPA, Fram, or any auto parts house brand and you will be perfectly fine.

Go at least 30,000 miles before changing it. They become more efficient as they accumulate the miles.

 

[JOD]

My opinion, worry less about the brand of filter and more about changing it more often that necessary. Look here and here for definitive proof that looking at a filter tells you practically nothing.

You'll probably ingest more dirt into the engine by monkeying with the filter unnecessarily than you will by one brand of filter vs. another. That said, you have to put something in there. The Motorcraft filter I have seems well-made, and when it's time for replacement I'll probably try the Amsoil EA air filter.

So, my advice: install a restriction gauge and any quality air filter, then leave it alone.

 

[electrolover]

Well im more of a 30k kinda guy myself. Not because its better or worse but because im cheap and I just plain forget about it.

 

[Donald]

My Cummins has a test button to check the air filter. They do not want you opening it up unless you are going to change it. OK I admit it, I did open it up once (just once) to have a look.

 

[dparm]

Try and get test results for the fine dust filtration. That's a better indicator of a good filter.

In general, the OEM-style paper ones are best for filtration (which is their primary job). All of the cotton and foam ones, oiled or unoiled, sacrifice that filtering for extra airflow. Not worth it IMO.

 

[JHZR2]

Buy a reasonable filter that is sturdy and seals well. I like the filters with the metal mesh over them really just from a strength and rodent potential point of view.

Dont change too often. Remember that the media does not filter, a "cake" of particles does the filtration.

There is a fine balance between having the media loaded (the "cake) and pressure drop going too high.

But it takes a long time for pressure drop to go too high. Filters are designed with high holding capacity with minimal pressure drop.

 

[Dave Hess]

50K miles down here and the air filter isn't that dirty. But that's my limit for any air fliter.

 

[Jim Allen]

electrolover: also go Here

 

[electrolover]

Thanks Jim. That kinda makes me want to let it go for a couple more months....

 

[accent2012]

Originally Posted By: Donald
My Cummins has a test button to check the air filter. They do not want you opening it up unless you are going to change it. OK I admit it, I did open it up once (just once) to have a look.


Warranty voided! lol

 

[OilFool]

Thinking outside the box from an incident I came across.

Best air filter is a dirty one as the soot itself acts as a filter.
Lower flow, but more filtering.
Counterintuitive, yes.
Think of a screen for a window... it'll let dirt thru... throw a paper towel on it and will let the dirt build on the towel and still fall through screen.

When I had to service a Buick my mom had, the whole filter had about 3/8" above pleats... Her service tech was never changing it. It was completely caked. I wish I still had the picture but Imageshack deleted everything. Honestly, the only caveat was the sluggishness and theoretically harder working engine to suck air... once I replaced the filter, it pepped up and used more gas. (I may actually STILL have the filter at her house now that i think of it)

K&N will flow more air, but flow more dirt through as well. my old used oil analysis on my old computer can prove this. Switched to a Pureone Air, and left it... the dirtier it became, the less showed up in the future analyses .

 

[Kruse]

Originally Posted By: gfh77665

Go at least 30,000 miles before changing it.


In the city or on the highway, fine. But your comment is a generalization that isn't always true. I live in ag country, over a mile off the highway. Half of my miles are on gravel roads or dirt. Blowing wind, with lots of dust, is a constant. 30,000 miles here would probably choke the engine to where it wouldn't run. The filter needs to be changed when it gets dirty.

 

[Sayjac]

Originally Posted By: JOD
My opinion, worry less about the brand of filter and more about changing it more often that necessary.....

+1 And even though the Fram EG AF's boxes say 12month/12k mi. that was a point made on my visit to the Fram test labs last fall. Longer is better than too short for AF filtration purposes. Without testing a 30k AF fci is nice 'general' length interval. Of course if living in a dusty area that factor would shorten the fci accordingly. Fwiw, Fram EG filters are my AF's of choice.

And, while I wouldn't worry about brand, my preference is for standard type AF's and not the cleanable/reusable variety.

 

[skyship]

The following points come to mind about air filtration:
1/ Don't fit silly after market air filter systems, as most produce worse results than the OEM system (K&N in particular). An after market air filter pressure drop sensor might be a good idea if it is practical to fit one.
2/ Buy the best quality air filter your bank manager will agree to and if in doubt stick to an OEM one.
3/ Be careful how you install it and check all associated pipes and connections for possible leaks.
4/ Don't change it until it is real dirty, it won't effect fuel consumption of a modern engine as the MAF / ECU will compensate. There is no real change interval, just inspect it every OCI.
5/ Don't pay any attention to air filter advertising as they keep quoting final filtration efficiency figures for a dirty filter, not the clean filter figures which are of more interest.

Silicon contamination of engine oil is real bad news as it causes a general increase in all wear metals and because a new air filter might be only 97% efficient in comparison with 99.5% for a dirty filter, a clean one might be allowing 6 times more debris into an engine compared with a dirty filter.

 

[Jim Allen]

Originally Posted By: skyship
The following points come to mind about air filtration:

5/ Don't pay any attention to air filter advertising as they keep quoting final filtration efficiency figures for a dirty filter, not the clean filter figures which are of more interest.



I could nitpick some of your other comments but this is the one that jumped out at me. Before I comment, I will ask you the difference between initial and final figures and how much dirt it requires to make the majority of the trip from the initial to the final figures.

Yes, I am laying a potential trap for you, or offering you a little education upgrade... because I have this answer.

 

[SteveSRT8]

Good for you, Jim!

It is precisely your information that completely changed my opinions of air filters for cars/trucks. deeply appreciated and money saving, too.

At least one other comment in Skyship's "opinions" is wildly platform specific. I'll just watch, wait, and learn...

 

[Jim Allen]

Originally Posted By: SteveSRT8
Good for you, Jim!

It is precisely your information that completely changed my opinions of air filters for cars/trucks. deeply appreciated and money saving, too.


Thank you! Nice thing to say that makes this otherwise mundane day.

 

[Rick in PA]

This was mentioned, but I feel the need to elaborate:

Install the air filter, THEN LEAVE IT BE. The next time you open the air filter box should be to install a new air filter. (OK, OK, I admit, I use to "clean" air filters years ago.) This was explained to me by an engineer at Donaldson Torit. The problem is that the seal on the the air filter is not designed for multiple uses. If you remove the air filter and then re-install it, there's a real risk that the seal won't "make" 100% to the air filter box. I seem to remember the engineer explaining this was where most of their "air filter problems" came from.

 

[walk23]

The most important aspect is sealing surface or how it seals in your box. I change my filter at 30,000 miles as it hardly is in dusty environments.