Change those Air Filters!

[Drew99GT]

I was goin for the "longer's better" approach recently because of the notions that a dusty air filter will further trap dirt better. Bot my parents vehicles have been boggy lately with decreased fuel mileage. Took the filters out last night and changed them and they didn't look too bad (not like some of the nasty black ones I've seen posted here) but pretty dusty with lots of dead grass type stuff between the pleats. HOLY COW! Both cars feel like they have about 20 extra hp. My pops was like, what the **** did you do to my truck

Used Purolators. Must say, they are built worse than Frams but Advance no longer carries Fram.

 

[gudmund]

can't say there is any difference between a Fram or a Purolator for my car being they are both the same filter "made in Korea". Anymore it looks like it depends on the vehicle and what company/country makes what filter for it. Have looked at Puro's/Fram's/STP's/Penz's so far and they all say "made in Korea" for my Suzuki Swift.

 

[Steve S]

As the filter gets filled? with dirt with the holes get smaller so less dirt gets in .when the filter is so clogged that air is restricted then there is a problem.

 

[road_rascal]

Drew, about how many miles do you think those filters had on them?

 

[Drew99GT]

I can't say for sure the mileage. Both had to be over 30,000 miles. Upon further inspection, they indeed were pretty loaded with dirt between the pleats. Absolutelly AMAZING how much better both cars run. I do live in a fairly dusty local, 10-15% relative humidity most days and my parents both drive on dirt roads routinly in the mountains, but like I said, a quick visual inspection of the overall filter didn't look that bad. I've seen some come out of engines that were BLACK with about a cm thick layer of crud on the surface.

 

[Drew99GT]

That doesn't surprise me Jason. I guess I just didn't consider how dusty my area really is and the driving on dirt roads. I just threw in new filters about 2 years ago and said forget about it and thought, hey, I better check those bad boys now. Glad I did.

 

[jason07-1zzfe]

Yeah you obviously drive in a very dusty environment.

Tracking MPG (long term) is probably the easiest way to figure when to change if you don't have a truck with a filter monitor in the housing.
Actually if you have a modern car with OBDII and a scanner you could periodically do some WOT runs and measure peak mass flow. Just be sure to correct the results to standard conditions so you can make a valid comparison. Although a change may not be significant unless you need that last .25hp. (WOT filter restriction might not matter at part throttle) So it goes back to monitoring mpg for real life effects.

 

[jason07-1zzfe]

Mine has 40k on it now and I'm still getting some of the best MPG's ever. I actually tested mine with equipment used to test air filtration media rather than rely on butt dyno and the media was insignificantly loaded after 24k. I predict I will get 100k easily with minimal increase in restriction.

 

[Drew99GT]

Just a bump. Changed air filters in the 2 cars mentioned after only a year, and viola, same incredible increase in performance. They were even less dirty than the ones I pulled out a year ago. I'd say the one in my moms car had about 12,000 miles; the one in my Dad's truck about 18,000. Man, feels like I put a blower on the 2 vehicles

I guess it really is dusty around these parts.

 

[The Critic]

I do mine every 30k.

But the Saturn's looks pretty dirty anyway after 24,000 miles...

Might have to change it.

 

[Dominic]

I change my filter every 15k or so, which is a little more than annual. At $5 a filter for my car, it's just worth it to me. I believe filters do filter better as they age, but they dont flow better!!

 

[Razl]

Does an air filter need to look dirty to warrant replacement?

I change my Saab's filter every 20,000 miles and my Honda every 30,000 miles. I do it like clockwork but it still looks clean. Compared to a new filter is looks not-as-white, but that's it

 

[BennyL]

maybe there's no dust where you live?

 

[Dominic]

Actually banging a filter or putting it through compressed air is not advised per filter makers. Read the box

 

[TheTanSedan]

My rule of thumb for many years has been air filters and wiper blades at six months. That worked well on the old carb'd V8's. Now, with a cold air intake modern V8, one year seems long enough. If that is 15m or 25m then it has done it's job.

Ideally, an air filter setup would be more like an offroad diesel: Pre-cleaner and two-stage filtration (one near permanent filter, and a more regularly changed filter). The seals, in all places, are the vital key.

CENTRI and DONALDSON make what I would like to be able to have. Terry long ago made the point that the air filter (my words) "far exceeds the importance of the oil filter".

Dusty roads . . . I'd go for 4-months/4,000 maximum. One week of dusty roads would be enough in some cases. Crushed limestone seems finer than talcum powder. I ruined one good pair of work boots long ago by not cleaning them daily after the work day (only lasted a few months versus a few years; REDWING).

 

[jmacmaster]

The idea that some dirt on the air filter makes it filter better is applicable only to a filter such as the K&N that is made of fabric that is oiled. The idea does not apply to paper filters. The dirtier a paper filter gets, the less air it flows. Yes, it may filter the air better, but at the expense of decreased air flow. It already filters adequately with no dirt on it. As soon as air flow is significantly interrupted, a paper filter should be cleaned or replaced. Clean it by banging it against a hard surface.

 

[cfromc]

I'd have to agree with the more often is better route for paper elements. Flow seems to decrease linearly in response to dirt held. And with it, so does gas mileage. I don't think 10K is too often, depending on conditions. I doubt if changing the filter too often would have any affect on an engine hitting 500,000 miles. As far as the statement about the air filter being more important than the oil filter...it is. Infinitely more important. The engine passes 9,000 gallons of air for every gallon of gas. I've seen engines die after a couple of weeks without an air filter yet my lawnmower has no oil filter and will probably live 20 years. It wouldn't make 1 year without an air filter.

 

[avette]

I've kept the factory filter for about 50K miles.
The mileage hasn't changed a bit after I replaced it with a new one.
In most cases a dirty looking filter is still not dirty enough to start restricting the airflow.
The most folks are judging the ability of the filter to flow by the amount of dirt they see on the panel.
This practice is totally misleading and wastefull.
In the "normal", not particularly dusty environment an average filter should last 40-50K mi, easily.

 

[avette]

quote:

---

Originally posted by Razl:
Does an air filter need to look dirty to warrant replacement?

I change my Saab's filter every 20,000 miles and my Honda every 30,000 miles. I do it like clockwork but it still looks clean. Compared to a new filter is looks not-as-white, but that's it

---

Try 40K mi next time.

 

[FleetFilter.com]

It depends were you live too. Around here in TEXAS there is alot of fine dust that clogs the filter, but makes it look clean.
Bryan