What is your air filter change interval?

[rrounds]

I'm in open loop more than most

No, I could not tell a difference in power. But at 8" the restriction would only take away maybe 2 to 3 hp(My butt dyno is not good enough to feel that), what it did though is to tell me when my air filter is starting to get dirty and add some restriction to the intake and not the air box that is adding the restriction itself.

Throttle Body
Inlet size 68mm
outlet size 65mm
I am looking at a straight through 70mm T/B for my S. That should get me 6 to 8 hp, more with a good tune.

ROD

 

[ltslimjim]

Just got an aFe Pro Dry S, and it is a complete upgrade to the K&N drop-in replacement I bought just 2 years ago when I first got the old Civic.

I'll just shake it + vacuum once a year, the end.

 

[widman]

Nissan requires me to change. Every 10000 km for the warantee. When it passes that period, 50000 km, i'll have 5 filters to put back in and change by restriction.

 

[Garak]

Geeze, is that what they specify down there, Richard? Up here, it's something like 30,000 or 40,000 km, at least on my Infiniti, and in every other late model Nissan/Infiniti manual I've seen.

 

[widman]

Yep, they like the money. Not cheap either.

 

[wirelessF]

On my Sentra I replace the filter every year.

For my Toyota tundra I inspect the filter every months and replace according to restriction gauge.

 

[Garak]

Originally Posted By: widman
Yep, they like the money. Not cheap either.


I'm fortunate, then. I just follow the more reasonable factory interval. While the G has two filters, I can get the Frams for under $10 a piece. OEM online are about twice the cost.

 

[zanzabar]

Originally Posted By: rrounds
Yes, I've read that paper. On my S2000 my gas mileage does drop after I get to about 15" to 20" of water. If all I did was cruise down a flat highway I know I could run more in. of water but I drive my car in the mountains(up to 10k ft. and up to 28% grades) and that does make my little 4 cyl.(2.2L) work hard and I'm up in the rpm's(7500+) so it does tax my air filter.

ROD


I'm curious, using your gauge and in these conditions, how often (time, mileage) do you end up changing your air filter?

N/M, I just found the poll thread and that pretty much answered my question. I think my conclusion is to keep filters in service at least 2x the manufacturer recommended interval. I may go with one of those filter minders, just for kicks, would be interesting to see if it is useful.

 

[KenO]

I change it when it looks so plugged dirt has completely filled up the pleats. The dirty they are, the better they filter;

 

[Jim Allen]

An air filter restriction gauge is the only reliable way you can tell when the filter is reaching a point where it needs to be changed. Because the level of dirt in the air is constantly changing according to the driving environment, any other means of determination is just guesswork. It's really that simple. Sometimes you can make pretty good educated guesses without a gauge, especially if your operating environment is more constant and predictable, but if you want to KNOW, you install the gauge.

 

[addyguy]

I change my air filters every 1-1.5 years about. Thing is, it ISN'T the dirtyness of the filter that makes me change it, it's always the degredation of the filter unit itself that does it - the foam seal around the filters gets dried out, shrinks and starts to crack past about 1.5 years.

This was the case with both my last car and my current one.

 

[HTSS_TR]

Originally Posted By: addyguy
I change my air filters every 1-1.5 years about. Thing is, it ISN'T the dirtyness of the filter that makes me change it, it's always the degredation of the filter unit itself that does it - the foam seal around the filters gets dried out, shrinks and starts to crack past about 1.5 years.

This was the case with both my last car and my current one.

This is the main reason I change the air filter, the filter media was fairly clean but the seal had some cracks after 3 years.

 

[Jim Allen]

both addyguy and HTSS-TR illustrate that one size doesn't fit all and you have to adjust to certain conditions... i.e. the deterioration of certain components in the filter. Might be a reason to go a few steps higher on the air filter quality food chain and get some with better foam in the seal or a different seal material altogether.

But not all filters are set up that way. Some have nitrile seals, or felt, or something that does not deteriorate as quickly. I haven't seen any cracked foam seals that I recall... none of my rigs have anything like that... so I would be interested to see pics if you took any or maybe you will take some the next time you swap out filters. Be educational to see what "bad" looks like in this case.

Actually, though, one of my small engines has a filter like that. I think it's the tiller, which is only four years old and has about 20 hours on it. I give the filter a cursory exam when I service the unit I should look at it again and see. Makes me wonder if I could fit a Donaldson Informer on small "one-lunger" and if a small engine like that would have teh suction to trigger the unit.

 

[doitmyself]

Jim,

You probably have similar winters that I experience in southern Michigan.

Sometimes the roads are dry, but covered in salt "dust". Do you have any idea if this salt "dust" builds up in the media enough to warrant annual replacement even though it doesn't look too dirty?

Thanks

 

[Loobed]

Salt mixes with water. The water spray can enter the air box. I would guess that if water vapor could pass through your filter, than saltwater vapor may also. I would also guess that your filter would clog sooner if you had salted roads.

 

[Jim Allen]

Yeah, we have the salt dust around here. I don't know whether salt dust clogs a filter faster than anything else but if you had a restriction gauge, you'd know. It really doesn't matter what the contaminant is, the filter stops it and when it stops enough of it, the filter gets restricted. The idea is to find the point at which the filter is restricted to the point where performance is affected. That is the ideal and cost-effective point for a change. The only way to find that point is with a restriction gauge. Anything else is just a guess.

Water, with or without salt, vapor doesn't pass thru all filter media. I know it WILL pass thru oiled cotton gauze filters but it will NOT pass cellulose. Synthetic & hybrid media... don't know. I suspect it will pass thru a synthetic media.

Here's a semi-relavent aside: Back in the early '90s, I had the opportunity to flow test a bunch of filters with the late, great Earl Davis at the K&N test facility in California. We had an air filter box from a then-current Land Rover and a variety of filters to test in it. One of the tests was to take the stock cellulose filter, new, test it dry, then soak it in water and flow test it again. It just about stopped flowing when wet. The explanation I was given is that the cellulose absorbs water and expands, blocking off the pores the air is designed to flow thru. One the filter dried, it was fine again but I was cautioned that if you put a lot of vacuum to a wet cellulose filter, it would damage it.

 

[calvin1]

Saltwater vapor?

 

[Loobed]

Originally Posted By: calvin1
Saltwater vapor?

Mist, salt water spray, or whatever that stuff is called that you find near the ocean.

 

[rrounds]

Originally Posted By: zanzabar
Originally Posted By: rrounds
Yes, I've read that paper. On my S2000 my gas mileage does drop after I get to about 15" to 20" of water. If all I did was cruise down a flat highway I know I could run more in. of water but I drive my car in the mountains(up to 10k ft. and up to 28% grades) and that does make my little 4 cyl.(2.2L) work hard and I'm up in the rpm's(7500+) so it does tax my air filter.

ROD


I'm curious, using your gauge and in these conditions, how often (time, mileage) do you end up changing your air filter?

N/M, I just found the poll thread and that pretty much answered my question. I think my conclusion is to keep filters in service at least 2x the manufacturer recommended interval. I may go with one of those filter minders, just for kicks, would be interesting to see if it is useful.


I have a little over 40k miles on my air filter and its now back up to 8" of vacuum @ WOT so right now I might change it at 4 years instead of waiting to get a high vacuum. If the filter still looks good at 4 years then I'll leave it on the car.

ROD

 

[thelazyhero]

Call it a waste of money but I just follow the manufacturers recommendation. I do all the work on my car as a hobby so I don't mind going out and buying a $20 OEM air filter. Figure this was money better spent than with another hobby.