How Often To Replace Air Filter?

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Aug 16, 2019
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Mine is about 2 years old. I took it out last week and it doesn't look dirty on the bottom of it, but it was a bit dusty when I tapped it on something.
Would it be overkill to replace it once a year, even though I only drive it about 3500 miles a year, in mostly non dusty conditions?
 
When I first started working on cars (mid 70's) the mechanic I learned from showed me how to use a drop or utility light and shine it through the backside of an air filter. He told me that if the light could be seen reasonably through the filter, then it did not need replacing. Please remember though that this was in the day of carburetors and round canister air filters.

There were no mass air flow sensors, electronic fuel injection, or variable valve timing engines. That being said, my new rule of thumb is to peel back the pleats and see what debris is in the folds. If it looks small and minute then I give it a light tap or vacuum and put it back. I also keep a new air filter on the shelf to also compare it to visibly. Paper and synthetic elements can discolor over time, from find dust and fallout since most intake air now comes from outside of the engine compartment. If the element paper is discolored, then I replace it.
 
Either replace it on a set schedule, which might mean throwing out a perfectly good filter, or change it based on how clean/dirty it looks. Every vehicle, climate/location, will vary that saying "yearly" or "every 6 months" is just guesswork. The owners manual for our cars say "inspect" the engine air filter. They leave it to your judgement as to replacing them.
 
If you're really cheap, you can sweep the pleats clean with a whisk broom and tap the filter repeatedly until dust stops coming off. Then reinstall it. Just make sure you don't break/puncture the filter media.
 
Mine is about 2 years old. I took it out last week and it doesn't look dirty on the bottom of it, but it was a bit dusty when I tapped it on something.
Would it be overkill to replace it once a year, even though I only drive it about 3500 miles a year, in mostly non dusty conditions?
Not only might it be overkill, but changing it too soon could work to your detriment. There are those who say that the accumulation of dirt on and in the filter enhances the filter's ability to, well, filter. I agree with that position. Of course, do your own research, consider all the factors involved, and decide what's right for you.
 
Popular wisdom is that a filter works even better as it's being used, until it doesn't. The idea is that big holes get plugged first leaving only small holes, so it actually filters better. [Who knows whether this is true but that's what "they" say.] In any case, at some point the grit has worked its way through the filter and it's no longer working.

But that would take a lot more than 3500 miles when driving in fairly normal conditions. [I drove through dust storms one summer and replaced a nearly new air filter after maybe 1,000 miles. It was literally packed with dust.]

We used to take our air filters out quite regularly and tap them, always knocking a bit of dirt out. But we didn't really know whether we were helping the cause or not.
 
When I first started working on cars (mid 70's) the mechanic I learned from showed me how to use a drop or utility light and shine it through the backside of an air filter. He told me that if the light could be seen reasonably through the filter, then it did not need replacing. Please remember though that this was in the day of carburetors and round canister air filters.
I mentioned this a year or so ago and people here thought I had lost my mind. Guess they never heard of this.
 
I generally change mine every 30,000 miles...and I drive in a winter climate (lots of road salt) and our springs around here produce a tremendous amount of pollen. And when I change it at 30,000 miles it usually looks pretty good still.
 
Not only might it be overkill, but changing it too soon could work to your detriment. There are those who say that the accumulation of dirt on and in the filter enhances the filter's ability to, well, filter. I agree with that position. Of course, do your own research, consider all the factors involved, and decide what's right for you.
Popular wisdom is that a filter works even better as it's being used, until it doesn't. The idea is that big holes get plugged first leaving only small holes, so it actually filters better. [Who knows whether this is true but that's what "they" say.] In any case, at some point the grit has worked its way through the filter and it's no longer working.

But that would take a lot more than 3500 miles when driving in fairly normal conditions. [I drove through dust storms one summer and replaced a nearly new air filter after maybe 1,000 miles. It was literally packed with dust.]

We used to take our air filters out quite regularly and tap them, always knocking a bit of dirt out. But we didn't really know whether we were helping the cause or not.
I went through some training on Baldwin filters and this is essentially what they said too. As filter restriction increases, efficiency also increases to a certain point where your efficiency decreased because the filter is so plugged. Someone else can probably put this in a lot more technical terms than I can.
 
I mentioned this a year or so ago and people here thought I had lost my mind. Guess they never heard of this.
Chris, I like the way you think....LOL. IT is called EXPERIENCE. Whenever I was being showed or taught something by someone older than me at the time, I tried to listen with intensity.......it seems that character or trait has been lost in our society of today.
 
Mine last from 30,000 to 70,000 miles. Unless a critter gets in there. They could probably go longer as I didn't notice any difference after changing them.
 
Clean and reuse every 40/50K miles

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