I use Fram air filters and change them every 20,000 miles. This seems to work well for me. I clean the MAF sensor every other change.
What is your air filter change interval?
- Thread starter Doog
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About every 2 years or every 30K miles.
Between 20 and 30K. Don't touch the MAF myself and I do a lot of driving in dusty conditions.
Once a year, which comes out to about 10-11k miles. It is cheap insurance for your car.
About 3-4 years or 40-45k miles.
1yr regardless of miles.
30,000 miles seems like what my cars call out.
Every 3 years or 30k - 40k miles.
Every 10k due to it getting very restricted
JHZR2
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I don't live in a terribly dusty area, so filters stay clean.
I might knock one out at some point to get the leaves and needles out, but the OE interval seems to do fine.
My turbo vehicles seem to show dirt earlier.
I might knock one out at some point to get the leaves and needles out, but the OE interval seems to do fine.
My turbo vehicles seem to show dirt earlier.
40K as they tend to not to get dirty so soon.
My cars factory air box practically vacuums the road so I change it around 25k miles or so. Generally Purolator.
Our fleet has the Ea ones from Amsoil. Every few months you simply pull them and blow them off with compressed air. Then we put them right back in.
Our fleet has the Ea ones from Amsoil. Every few months you simply pull them and blow them off with compressed air. Then we put them right back in.
Every few years, or 30-40K.
Everything got a new air filter last summer since very favorable after MIR pricing was available.
We apprently don't live in a very dusty area, since they are dark but not opaque upon removal.
As long as there are no tears or so much restiction that the filter cannot flow enough air to meet the engine's requirements, a filter should be good to go.
Everything got a new air filter last summer since very favorable after MIR pricing was available.
We apprently don't live in a very dusty area, since they are dark but not opaque upon removal.
As long as there are no tears or so much restiction that the filter cannot flow enough air to meet the engine's requirements, a filter should be good to go.
Here is my Don Quixote Moment:
Lotta money being wasted by some of you people. Don't you know that air filter efficiency improves as the filter loads up? You are actually doing more harm replacing a slightly dirty filter for that reason, plus when you open the air box up, you are letting dirt in by accident. On top of that, as you will read below, fuel economy isn't effected until the filter gets so plugged the car basically won't run. Power may be effected but since the average filter has 20-40 percent more airflow capacity than the engine can use, you have that percentage to play with before power is effected. There's where a restriction gauge plays a part (read below).
I have access to a flow bench (Superflow SF600) and tested the stock air filter assembly on my F150. It flowed an average of 621.58 cfm @ 28" H2O. When I calculate the airflow needs of the 5.4L engine at it's rated maximum power (300 hp @ 5000 rpm) it's 480 cfm figuring 100% VE, so I have 23 percent to play with (it's less really because 100% VE isn't often achievable... usually 0.85 is more real world and that gives me nearer my 40 percent)
So, my cars now have air filter restriction gauges and the air fitlers aren't touched until restriction reached 2.5kPa or, if I have the manufacturers spec, I'd use that. Actually, 2.5kPa (about 10" H20 may be conservative)... the generic upper limit I've found is 5kPa (20" H20). Going on about 5 years with our Honda and three on the F150 and neither is anywhere near 2.5 kPa.
LookHere: Air Filters & Fuel Economy http://www.fueleconomy.gov/feg/pdfs/Air_Filter_Effects_02_26_2009.pdf
This 2009 report tests the effect of dirty air filter on fuel economy using standard EPA dyno routines. They used later model EFI cars (2003-2007)and one 1975 carbureted car. The conclusion what that the fuel injection could compensate for the restriction up to the point where the car's performance had deteriorated to barely running and fuel economy decreased only by a percent or so. Performance degraded, of course. The carbureted car was more effected but fuel economy wasn't lowered by nearly as much as "common knowledge" dictates... only 2.5 percent.
In every case lower end performance was unaffected until the restriction reached the level at which insufficient air was being inhaled. Performance dropped mightily at that point but the EFI could still trim fuel to keep the mixture about right. They found that in "normal" driving situation, the car was almost unaffected by a clogged filter because the airflow needs were so low. In a few cases, the filters were so clogged that the engine sucked them into the intake tube when they tried to make full power tests.
Lotta money being wasted by some of you people. Don't you know that air filter efficiency improves as the filter loads up? You are actually doing more harm replacing a slightly dirty filter for that reason, plus when you open the air box up, you are letting dirt in by accident. On top of that, as you will read below, fuel economy isn't effected until the filter gets so plugged the car basically won't run. Power may be effected but since the average filter has 20-40 percent more airflow capacity than the engine can use, you have that percentage to play with before power is effected. There's where a restriction gauge plays a part (read below).
I have access to a flow bench (Superflow SF600) and tested the stock air filter assembly on my F150. It flowed an average of 621.58 cfm @ 28" H2O. When I calculate the airflow needs of the 5.4L engine at it's rated maximum power (300 hp @ 5000 rpm) it's 480 cfm figuring 100% VE, so I have 23 percent to play with (it's less really because 100% VE isn't often achievable... usually 0.85 is more real world and that gives me nearer my 40 percent)
So, my cars now have air filter restriction gauges and the air fitlers aren't touched until restriction reached 2.5kPa or, if I have the manufacturers spec, I'd use that. Actually, 2.5kPa (about 10" H20 may be conservative)... the generic upper limit I've found is 5kPa (20" H20). Going on about 5 years with our Honda and three on the F150 and neither is anywhere near 2.5 kPa.
LookHere: Air Filters & Fuel Economy http://www.fueleconomy.gov/feg/pdfs/Air_Filter_Effects_02_26_2009.pdf
This 2009 report tests the effect of dirty air filter on fuel economy using standard EPA dyno routines. They used later model EFI cars (2003-2007)and one 1975 carbureted car. The conclusion what that the fuel injection could compensate for the restriction up to the point where the car's performance had deteriorated to barely running and fuel economy decreased only by a percent or so. Performance degraded, of course. The carbureted car was more effected but fuel economy wasn't lowered by nearly as much as "common knowledge" dictates... only 2.5 percent.
In every case lower end performance was unaffected until the restriction reached the level at which insufficient air was being inhaled. Performance dropped mightily at that point but the EFI could still trim fuel to keep the mixture about right. They found that in "normal" driving situation, the car was almost unaffected by a clogged filter because the airflow needs were so low. In a few cases, the filters were so clogged that the engine sucked them into the intake tube when they tried to make full power tests.
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Absolutely agreed Jim.
But my car's air box is vertical, with the inlet down in the front bumper, so I don't have to worry about dirt getting into the intake tube when servicing the filter. But with the intake so close to the road it really picks up the crud!
Our trucks will easily ingest soil during a filter change if you are not careful as the filter is actually above the throttle body.
But my car's air box is vertical, with the inlet down in the front bumper, so I don't have to worry about dirt getting into the intake tube when servicing the filter. But with the intake so close to the road it really picks up the crud!
Our trucks will easily ingest soil during a filter change if you are not careful as the filter is actually above the throttle body.
Steve: Yes, every situation is different, exceptions to every rule, and no matter what, you have to adjust to the situation. What would interest me is if you installed restriction gauges on some of your trucks and see just how far they could go before they indicated a need to change (or clean in your case).
My point above is general in nature and directed more at the, "I change my filter every year." Or, " I change it a X-miles." I'd be willing to bet that the majority of those filters were still very serviceable. And you can't always tell by looks. Widman (you can look him up here on BITOG) runs an outfit in very rural Bolivia and is probably testing the limits of air filter life and performance daily. He's a restriction gauge proponent (and my personal air filtration hero ( : < ) and has seen utterly caked filters that still had very low restriction... proving you can't always tell by looks alone.
Final point is that constantly pulling a filter to look at it may disrupt the sealing areas and you can create a dirt leak in doing so. Seal deterioration is the sole legitimate reason IMO for a filter change based on time. How long they remain viable is variable and debatable and probably a combination of the quality of the sealing material, the way it's designed and how many times it gets molested.
Which brings us back to the restriction gauge. You don't touch the filter until you see enough restriction to indicate service in needed. Probably a good idea to reset the gauge every so often to make sure it's working.
Forgive my pedantic semi-tirade. This is my quest and you are my windmills.
( : < )
My point above is general in nature and directed more at the, "I change my filter every year." Or, " I change it a X-miles." I'd be willing to bet that the majority of those filters were still very serviceable. And you can't always tell by looks. Widman (you can look him up here on BITOG) runs an outfit in very rural Bolivia and is probably testing the limits of air filter life and performance daily. He's a restriction gauge proponent (and my personal air filtration hero ( : < ) and has seen utterly caked filters that still had very low restriction... proving you can't always tell by looks alone.
Final point is that constantly pulling a filter to look at it may disrupt the sealing areas and you can create a dirt leak in doing so. Seal deterioration is the sole legitimate reason IMO for a filter change based on time. How long they remain viable is variable and debatable and probably a combination of the quality of the sealing material, the way it's designed and how many times it gets molested.
Which brings us back to the restriction gauge. You don't touch the filter until you see enough restriction to indicate service in needed. Probably a good idea to reset the gauge every so often to make sure it's working.
Forgive my pedantic semi-tirade. This is my quest and you are my windmills.
( : < )
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Interesting test results. But mine are always visibly dirty to the point where they are black enough not to put back in. Plus there is always leaves and tree debris in there. I live in a wooded area so there is a lot of dust. Same with the house furnace air filters. 120 days and they are done.
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Originally Posted By: Doog
Interesting test results. But mine are always visibly dirty to the point where they are black enough not to put back in. Plus there is always leaves and tree debris in there. I live in a wooded area so there is a lot of dust. Same with the house furnace air filters. 120 days and they are done.
No doubt it looks nasty but is it restrictive? You can't say without a gauge. Widman (you can google him here if interested enough) had some pics of nasty looking filters that were still within restriction tolerance. Just depends on what you are used to seeing.
Interesting test results. But mine are always visibly dirty to the point where they are black enough not to put back in. Plus there is always leaves and tree debris in there. I live in a wooded area so there is a lot of dust. Same with the house furnace air filters. 120 days and they are done.
No doubt it looks nasty but is it restrictive? You can't say without a gauge. Widman (you can google him here if interested enough) had some pics of nasty looking filters that were still within restriction tolerance. Just depends on what you are used to seeing.
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