asasa11

Do you change air filter by looks or miles?

Messages
7,838
Location
Champlain/Hudson Valley
[email protected] 30,000 + or -. Enough big dirt to be seen not merely a mild darkening. INCONCLUSIVE ANECDOTE: My car came with service records and I believe the air filter was in 30,000 miles when I got it so I took it out. Sand fell from the dirty side freely. I tapped the filter and the rain of dirt never stopped. I had seen enough and replaced the element figuring it was "truly filthy". Yes, I know it's not an engineering term. Who's to say those filter minders are made / inspected using any real QC? I like the idea though.
 
Messages
2,942
Location
Western S.C.
Ideally, you should change by restriction. If you change by looks, you might, just maybe, be able to judge correctly. If you change by mileage or time, you're making a wild guess. Your conditions probably are not the same as whatever the manufacturer assumed in specifying a change interval.
 
Messages
58
Location
Kansas
Originally Posted By: Linctex
Originally Posted By: Bluestream
Remember filters become more efficient with use
Yeah, but nobody really wants to hear that.
About 50 years ago, Southwest Research Institute took a Mack diesel engine and installed radioactive piston rings in it. That way they could monitor piston ring wear by the amount of radiation in the engine oil. After establishing a baseline, they gradually fed fine dust into the inlet of a dry paper element. There was a spike in the wear until a “cake” of dust had developed on the filter element then the wear quickly dropped to almost nothing as in their previous baseline. They also installed an oil bath air filter but as I recall quickly discontinued that test due to excessive wear. This test was published by the Society of Automotive Engineers (SAE) but I haven't been able to find it on their website. Since reading that paper years ago, I seldom replace air filter elements but wait until the rubber seals start to get hard. I do clean them by gently tapping the dirt out of them. I have over 350,000 miles on two different vehicles and have not experienced any obvious loss of performance or loss of fuel mileage.
 
Messages
3,279
Location
On another site
Originally Posted By: jacobs
Originally Posted By: Linctex
Originally Posted By: Bluestream
Remember filters become more efficient with use
Yeah, but nobody really wants to hear that.
About 50 years ago, Southwest Research Institute took a Mack diesel engine and installed radioactive piston rings in it. That way they could monitor piston ring wear by the amount of radiation in the engine oil. After establishing a baseline, they gradually fed fine dust into the inlet of a dry paper element. There was a spike in the wear until a “cake” of dust had developed on the filter element then the wear quickly dropped to almost nothing as in their previous baseline. They also installed an oil bath air filter but as I recall quickly discontinued that test due to excessive wear. This test was published by the Society of Automotive Engineers (SAE) but I haven't been able to find it on their website. Since reading that paper years ago, I seldom replace air filter elements but wait until the rubber seals start to get hard. I do clean them by gently tapping the dirt out of them. I have over 350,000 miles on two different vehicles and have not experienced any obvious loss of performance or loss of fuel mileage.
Good stuff-- if filtration element is still filtering and the edge seal is still pliable to form a seal it is good to go. Before reading the testimonial above, my thought was that without a restriction gauge telling you when to [clean or replace], miles should be used as a general guide and adjusted for conditions. Mine went 40k before I opened them up, 30k with a lot of dusty driving.
 
Messages
354
Location
Boise, Idaho
I do mine by looks. We have a lot of dust in the air here. Open fields being worked for planting or harvest raises a lot of dust. Building in new subdivisions that take over some of the fields old farmers are selling off works up the dust. Narrow road widening projects can work up the dust. The air can get a bit dirty here. As a result I check mine every oil change. If dirty it gets replaced.
 
Messages
11,000
Location
Florida, Cape Coral
I go by miles since I need to remove it to see how it is doing on the engine side. I adjust my change interval after the first manufactures recommended change. Ed
 
Messages
1,402
Location
MT
I change it annually during the spring oil change. It's only $17 so why not? It still looks pretty clean too but I change it anyway.
 
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