I came across an old thread that completely trashed the K&N filter for not really doing its job as well as an average air filter. I have one installed right now, but I've only put about 500 miles on it. Keep it or remove it? Sticking with the common goal among all of us, I want my car to go for many miles, so I'll take any necessary steps to ensure that happens.

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Never be ashamed to ask for help.

1985 300D
1987 300SDL
1970 Jaguar E-Type OTS
2002 Dodge Intrepid (Traded In)
2011 Ford Crown Victoria

Up to you, I sold mine.

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83 SD

84 CD

Much information here

Even more here, a few hours of reading.

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1999 Mercedes E300TD daily driver sold at 238K miles 106K miles were mine, rust worm got it :-(
2006 Mercedes CDI new daily driver! 56,000 miles May 2016 now 85,625 Apr 2018 and Apr 2019 101,000 miles Apr 2020 109,875. March 2024 135,250

I would personally never use one.

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'98 E300 turbodiesel

Take internet info with a grain of salt. Some is biased by competition, even if it's not readily apparent, and some is just repeating. I've used a K&N filter, the stock-fit type, on at least three different vehicles in very dusty conditions (west Texas) and suffered no ill effects because of it. I have a Ford 6.9L that was used by the previous owner in west Texas oil fields, with caliche clay roads, and it currently has just under 500K and a K&N filter when I bought it.

I don't necessarily go along with some of the performance hype but if you want a well-built, cleanable filter then enjoy. I certainly don't see any sense in throwing it away.

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Sam

84 300SD 350K+ miles ( Blue Belle )

If you do not want to pay for throw away Air Filters (I had a K&N on mine for over 2 years because the Blow-by would ruin the Paper Filters) and you have a Federal Car.
Washable Air Filter and Intake Mod , With Larger Breather
http://www.peachparts.com/shopforum/showthread.php?t=280376
And, before the Hot Air Intake folks chime in I have disproved that. The only time the Under the Hood Temp rises is when the Car idles. Even moving in stop and go city Traffic there us enough air flow under the Hood that the under the Hood temp is only 5-10 degrees higher than the outside temp (this is with out any sort of Belly Pan).

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84 300D, 82 Volvo 244Gl Diesel

I would never run one ever in any car I cared about.

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

i ran one on my old ranger... i had to replace the MAF sensor at 65k... i wouldn't use one anymore

I had previously been using a K&N that fit into the Stock Air Filter Housing.
My 2 cents worth is in several of the threads on K&Ns.

I will say that between the Air Filter and the Hole that went down into the intake I always had a film of Oil from Blow-by.

If dirt had actually passed through the Filter I believe I would have felt something gritty in that Oil film. It never felt gritty.
However, the Rubber on the K&N was very stiff and

I worried it would not seal well in the Air Filter Housing. I put a bead of Silicone Sealant around the sealing areas when I installed it and made sure it sealed.
FRAM has washable with Dish Soap and Water Filters from some models. The Washable Filters numbers start with WA instead of CA in the Fram part numbers.
I did an air intake mod on the Mercedes because they do not make a washable one for the Mercedes but I did buy a set of 2 for my Chevy Astro Van (I bought 2 because they can take a long time to Dry out after being washed).
Yor local Auto Parts Store most likely will not sell the Washable Fram Air Filters because they want you to keep buying the throw away ones.

One of the other members has also told me that Amsoil makes a soap and water washable Filters.

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84 300D, 82 Volvo 244Gl Diesel

My '84 had the factory style K+N on it when I got it years ago and now has a washable cone type filter. The car now has 380,000+ and runs great. I've read some of the so called tests and such against K+N and I'm not buying it. K+N has a huge share of the market and it would be to someones advantage to dis' them. Do what makes you feel comfy.

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Diesel-guy

The Dodge Neon was also a big success from a numbers standpoint, which apparently means that it is better than the Mercedes models that it out-sold?

I don't buy that logic either.

K&N was quite secretive about its filtration efficiency for as long as I can remember, so people had to do their own tests. I don't know if K&N has changed their methods and now publishes accurate, standardized filtration efficiency numbers, they might.

However, the K&N filter is not terrible, it does filter. In a gas car with a MAF sensor, I would strongly discourage it. On an older diesel Mercedes, the engine is probably pretty loose already, and will outlive the body of the car, so even if it is less of a filter than Mercedes stock filter system, it is probably "good enough", you decide.

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Gone to the dark side

- Jeff

on a GAS car, the filters can be used effectively. but cleaning, properly drying and properly oiling with the correct oil is critical to longevity and performance.

I put one on my 2000 astro van at 18K and it's got 190K on it now, and there is a maf sensor in the intake right above the air filter box.
no problems ever. I clean it with good gentile degreaser, gentle, water rinse, and dry overnight, never with air pressure. then gently spray the K&N oil on the dirt side ONLY
no issues, no problems!

I would NEVER put one of these on my diesels! WAAAAY too much air passes through them!

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

Unlike Fuel, Hydraulic and Oil Filters Air Filter information does not have the level of filtration spec posted.

Part Number:46117UPC Number:765809461178Principal Application:GM Cars & Trucks (92-05)All ApplicationsStyle:Air Filter PanelService:AirLength:11.563Width:6.050Height:1.660CFM:320
(This is what you would see when you look up the Wix 46117 for my chevy Astro Van. Zero info on what sized particles will be filtered.)

Unlike the Oil that actually makes contact and gets between the moving parts the bulk of the Air that goes into the cylinder and turned into exhaust gasses gets expelled from the Engine.
So not as much of what ever particles are in the intake Air actually stay inside of the Engine to do harm.

I am looking at a Fram Filter box and it has "Filters out 99% of harmful particles". But, it does not say 99% of what sized particles and that makes that information somewhat useless.

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84 300D, 82 Volvo 244Gl Diesel

I always got filtration efficiency information on air filters, whether for my CAT or for an industrial air-handler.

Any dust can do damage. It is abrasive to the turbo and intake, can cling to cylinder walls, etc. I know that you're not arguing that air filtration is not necessary.

Less and smaller particles will always benefit the engine.

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Gone to the dark side

- Jeff

I run a K&N filter and filter lid on my 67 Camaro to let it really breath, and flows extremely well. Of course, it doesn't see dusty roads and such as most cars

It is unbelievable what these MB diesel filters can hold and stop (see below). The inside pleats were pretty clean as well as the inside area of the filter box.

The air flow and capacity is quite high. This was on a car I purchased. I would never let it close to this bad on one of my cars

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1987 300TD 147,000 miles- Palomino leather interior, 1995 facelift and body cladding, E350 wheels, Rebuilt suspension and sport springs, rebuilt turbo, New Monarch injection pump and injectors....and the list goes on and on...