I use a regular fram paper element filter. I drive in a fairly non-dusty environment. (city/rural mix - paved) My filter never looks very dirty. It has gotten a bit darker over time. The last time I looked at it I took my shop vac to it and sucked off what I could. Why should I buy a new one?
Why Change your air filter?
- Thread starter Winston
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I think you could even extend from the oem recommended intervals.
Did you check to see if you got all the little particles (particles too small to see with the unaided eye) off the paper and completely restored the chemical treatment that came on the new filter paper? If you only want your filter to look 'clean enough' then you don't need change it. You might want to reconsider your plan when parts of the paper become brittle and get sucked into the engine. It's going to be tough to justify the savings realized by not changing an air filter, in any case. If you don't want to change the filter you should at least remove it when pieces start vanishing into the engine. Also, remember that if you plan on not keeping your car and selling it, that the condition of an air filter might be of interest to the buyer and is easy to check. In the end you will be doing something that most people don't do.
JHZR2
Staff member
some vehicles have essentially a resistance meter around their filter, which gauges how dirty the filter actually is. The increased resistance increases pumping losses of the air pump that is your engine, requiring more fuel to be burned, etc.
A dirtier filter should clean the air better, theoretically, but then again, paper filters do break down with time, and probably start letting more through.
JMH
A dirtier filter should clean the air better, theoretically, but then again, paper filters do break down with time, and probably start letting more through.
JMH
??
Cellulose (paper) air filters don't have chemical treatments. Some are oiled, but other than normal curing of the media, there is no chemical treatment.
Re: bits of the filter breaking off.
The filter itself looks completely in tact. No bits are falling off. I was wondering how long it would take for the filter to start disintegrating, but I do not think I am anywhere near that point.
I was waiting for the, "it is so cheap you should just change it" arguement. I am glad no one tried it. It is a reasonable arguement, but not the point of my post.
The filter itself looks completely in tact. No bits are falling off. I was wondering how long it would take for the filter to start disintegrating, but I do not think I am anywhere near that point.
I was waiting for the, "it is so cheap you should just change it" arguement. I am glad no one tried it. It is a reasonable arguement, but not the point of my post.
You shouldn't change it. Most people change them too soon. SAE even did a paper on how air filter change intervals were too short in most instances. I had the same thoughts and proved it in my car with testing. The air permeability of my filter media only dropped about 4% from new after 24k miles. That is insiginificant. And easily supports the SAE's posistion of 80-100k would be more suitable for most. Mine could go longer than that based on testing but I would change it within about 7yrs max, just as a conservative safety factor. I didn't test the strength of my media because it wouldn't have degraded much but I am basing that time on other testing I have done.
I was talking about those that leave the air filter in for long time periods like three to five years, or more. I've seen filters with hole in them the size of a quarter. I think that the holes will restore air flow for a used filter but I'd rather have a new filter. The paper in a new filter is cured and/or treated and I don't think that this paper is suitable for reuse after cleaning, maybe just a smack to drop loose dirt before returning it to the housing. A good way to judge a filter is by the pressure drop across the filter when in actual use, like the big trucks do. I think such a gauge would be useful but I've never seen one for sale to add to a passenger car. People must just change the filter and not worry if it's too soon or too late. Maybe they don't even know, it's just something the mechanic does and who cares one way or the other, except those that cross this forum.
No. The effects of partly open throttles and other system restrictions would completely overshadow anything but acompletelly pluccge air filter.
The difference between a new element and one that should have beeen replaced some time ago is less than 10 in-H2O pressure drop. That's not much pressure. About 0.36 lb/in^2.
Vacuuming may get the bigger pieces out of the way, but it seems to me that part of how a paper filter works is the some of the particles get lodged in the holes and gradually block the airflow. You will never get them all back out of the filter, as they have become mechanically lodged and a simple vacuum wont have enough power to pull them back out.
This results in a slow but steady drop in airflow. This will probably be slow enough you wont really notice it, but at some point it will reduce efficiency, power, gas mileage. You probably wont hurt anything, but the system just wont be working as well as it should.
Carbureted engines will probably show the effect first, as modern engine controls should automatically compensate and keep the air/fuel ratio correct. I have seen engines in the 60;s with filters so plugged they were obviously running rich, along with the poor performance that went with it. But those people just never did any maintenance. They would never have bothered with vacuuming, since they couldn't even see their way to do a simple replacement.
Now it must be said. Is that effort worth it for just a few dollars and the best performance?
This results in a slow but steady drop in airflow. This will probably be slow enough you wont really notice it, but at some point it will reduce efficiency, power, gas mileage. You probably wont hurt anything, but the system just wont be working as well as it should.
Carbureted engines will probably show the effect first, as modern engine controls should automatically compensate and keep the air/fuel ratio correct. I have seen engines in the 60;s with filters so plugged they were obviously running rich, along with the poor performance that went with it. But those people just never did any maintenance. They would never have bothered with vacuuming, since they couldn't even see their way to do a simple replacement.
Now it must be said. Is that effort worth it for just a few dollars and the best performance?
How different will be this gauge reading from manifold absolute pressure reading? ScanGauge reports that. Do these readings even corelate?
I tested the oe paper filter on my 84 Honda prelude
back in the 80s and I found the wear metals
went up quite abit after I went past 20k. The new
Honda filters appear to clean much better than the old filters, but at point do they start dumping
downstream? My current oe filter appears to be made from a synthetic material and works very well.
I thought I would mention that I tried 2 Deuch?
filters from Autozone on my 87 legend and started
having starting problems within 5k miles. What amazed me was that they looked like very good filters but they did not flow like the oe. I thought at that point it was easier to stick with the oe. Do you find that other brands work better
now? My Acura filter is 25 bucks but it does work very well.
back in the 80s and I found the wear metals
went up quite abit after I went past 20k. The new
Honda filters appear to clean much better than the old filters, but at point do they start dumping
downstream? My current oe filter appears to be made from a synthetic material and works very well.
I thought I would mention that I tried 2 Deuch?
filters from Autozone on my 87 legend and started
having starting problems within 5k miles. What amazed me was that they looked like very good filters but they did not flow like the oe. I thought at that point it was easier to stick with the oe. Do you find that other brands work better
now? My Acura filter is 25 bucks but it does work very well.
Why indeedt? I mean, after all, new cars are cheap and disposable, right?
When I had to buy a new car I went through major sticker shock. You know, the "it was more than the down payment of my first house" thing. So, since filters are cheap and cars are not, the smart money seems to say swap the filters at regular intervals and be happy.
Bob W.
It's not about money. It's about optimizing air filtration.
Yes, agreed. I'll add air flow to that too. I can detect better acceleration after changing my air filters using 30k miles intervals. It's not scientific, but it's noticeable.
Most air filters restrict flow to some degree so I rather stick to the manufacturers intervals. Ever run a car without one? You'll see what I mean
This is a ridiculous arguement.
How cheap can you be to try to say you never have to change your air filter?
Easy test, take it out, hold it up to the sun and see if you can see light through it.
If you can, put it back in and continue driving.
But still, change it every 2 years at least.
People to cheap to change it are probably the same people complaining that their fuel economy is crap.
Optimizing air filtration? Gimmie a friggin break.......
How cheap can you be to try to say you never have to change your air filter?
Easy test, take it out, hold it up to the sun and see if you can see light through it.
If you can, put it back in and continue driving.
But still, change it every 2 years at least.
People to cheap to change it are probably the same people complaining that their fuel economy is crap.
Optimizing air filtration? Gimmie a friggin break.......
Patman
Staff member
I don't think it's being cheap and it is true, the longer you leave your filter in, the better it filters. It's a proven fact. Only if the media gets damaged, will the filtration get worse.
This is the same "flow versus filtraton" issue that has captivated all of us, and which is present not only here but in the oil filter arena, as well. It raises valid points, I think.
I suppose the physicist would say there are two curves on the graph, and where they interect is the sweet spot between these ideals of flow and filtration.
The problem I see with Patman's position is how do you tell when the filter has reached the intersection of these points? Where does the saturation point exist and air flow decreases? When does this matter? How much difference does a percent or two decrease make?
We do have Spicer's analysis, excellent as it is. But how does it apply to daily driving? I dunno the answer, but it seems to me that the costs and energy associated with this are more than replacing a paper filter per mfg specs.
Just my 0.02ppm.
Bob W.
Patman
Staff member
Bob, for someone like me who takes my car to the dragstrip, I could tell if the air filter was getting clogged by the timeslips. If I suspect the filter is clogged, I could change it between rounds and see if the time improves. I did this with my last car, when the original air filter had 80k on it. My trap speeds only improved very slightly (0.3mph), so it showed me the filter wasn't really restricting the airflow much, if at all.
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