K&N Air Filters - Any real mpg and acceleration benefit?

[mountainwalker]

Do they have any real mpg or acceleration benefit over standard air filters? Many people seem to swear by them.

 

Also, how often would you clean them? K&N says once every 50,000 miles but it's a filter and will clog like others, even if it takes a little longer, so I'd probably clean mine once/year.

[idosubaru]

tiny bit. in college i was putting a ton of miles on my XT6's and went with a K&N filter and dynomax muffler. it was good for maybe 2 or 3 mpg better on all highway cruising. outside of that i didn't notice any in town mpg or acceleration benefits.

 

don't recall how often i cleaned it but i would think it was more than every 50,000. i put a lot of miles on one filter as i used it on two or three different XT6's.

[Petersubaru]

Do they have any real mpg or acceleration benefit over standard air filters? Many people seem to swear by them.

 

Also, how often would you clean them? K&N says once every 50,000 miles but it's a filter and will clog like others, even if it takes a little longer, so I'd probably clean mine once/year.

..you be the judge @ http://www.bobistheoilguy.com/cms/index.php?option=com_content&view=article&id=66&Itemid=76

[mountainwalker]

Wow thanks for posting that test. Looks pretty exhaustive. I don't like that the K&N may be passing more dirt to the engine and damaging it in the process of passing more air through - do you think this could be a problem?

 

I'm wondering if I'm just better off using standard cheaper air filters and just replacing them more often to maintain performance, say every 6 months.

[SubieDaddy80]

WIX filters baby!

[Olnick]

The general feeling that I've picked up over the years is to not use a K&N on the Subaru. Our cars breathe very well with a clean standard air filter.

Plus I've heard that oil can mist from the K&N and collect on the sensor wires in the MAF causing problems.

 

Just a different perspective!

[mountainwalker]

SubieDaddy80, thanks, can you tell me a little about WIX filters? Are they folded paper style filters? Are they any better than any other folded paper-based filters? Are they expensive? How much does the WIX filter for your Subaru run and where did you get it?

 

Olnick, thanks for your thoughts - that's what I came across after researching K&N.

 

All in all I think it may be best to do what I did with my good ole Volvo 240 DL, which was to use an inexpensive basic generic air filter and change it every 6-9 months.

[WoodsWagon]

Plus I've heard that oil can mist from the K&N and collect on the sensor wires in the MAF causing problems.

 

Yup, used to carry a can of MAF sensor cleaner in my truck because of this. It would throw a MAF code once a month. Previous owner had put a K&N cone on it and chucked the stock airbox. I was not pleased. I finally found a paper filter that I could clamp onto the "Cold air intake" tube and voila! the MAF codes and repeated cleanings went away.

[idosubaru]

properly oiled the MAF won't be a problem on a subaru. i'm not recommending them. you don't sound like you have any compelling reason to get one, just go standard. i was putting mad mileage, well over 30k+ a year and used the same one on multiple vehicles so i got my money's worth.

[eppoh]

..you be the judge @ http://www.bobistheoilguy.com/cms/index.php?option=com_content&view=article&id=66&Itemid=76

 

 

Nice comparison, but it needs to be considered in context;

 

I have used paper and K&N filters for years. My experience is that K&N filters in modern vehicles allow a "little"more power on the top end at the expense of MPG in the low and middle range. My belief is that modern injections systems with MAF's and O2 sensors cause the injection system to increase fuel flow to keep the AF ratio where it is programmed to be- thus with more air, more fuel.

 

This is also my experience in my diesel pickup up. The turbo spools faster, but I lost about 1 1/2 mpg daily driving. Top end is noticeably stronger.

 

Now as far as allowing more dirt in the engine, consider this. I drive a vehicle until it has between 250 and 300,000 miles before I trade. Even using an oil cotton filter like the K&N, I have never worn out a modern engine. No major blow by, no ruined bearings, etc.

 

So, the decision as to use a "high performance" should not be affected by "more dirt". It is of no effect, IMO. I won't do it again because of it's affect on daily driving mpg.

 

YMMV

[mdjdc]

I have used K&N filters on my subies for nearly 15 years and I have never gotten a code for the MAF. The filter requires good cleaning and oiling to specs. Over oiling will lead to fouling of the MAF.

 

I have enjoyed the improvement in performance and fuel mileage.

 

I'm not endorsing the filter over others, just fiving my experience. It really helped with performance with my EA82 vehicles and I have continued to use them with my new gen cars. If they were contributing to engine breakdown, I don't think they would still be in business, nor do I think that race cars would be equipped with them.

 

When you look at the comparison of the two oiled filters in the test, you must attribute some of the color to the oil. The secondary filter was right atop the primary and some of the oil is going to aresol onto the secondary filter, leading to a darker color. In the old days oil bath filters were the norm and only discarded due to inconvience.

 

Just my 2 cents

[mountainwalker]

Weighing all the comments and factors, it seems the safest and least time-consuming thing for our family use mixed town and highway driving is just to use a standard filter. We put on only light regular miles outside of special trips, certainly less than average, and at least 1/3-1/2 of our regular driving is around town 30-45 mph.

 

The WIX filter was only $11.82. At that price easy to change every 6-9 months if I needed/wanted to.

 

Thanks to all for the very helpful info and suggestions.

[SubieDaddy80]

Funny little side note. When I worked at Schucks and we started to set-up those little K&N displays with the ball floating in air. K&N SPECIFICALLY told us NOT to put the oil on the filter when putting it in the air flow display! Came to find out that when the oil is added, it actually has LESS air flow than the standard air filter! Yes, I am dead serious and you can argue it all you want but I saw it right before my eyes. Just a little food for thought.

[mdjdc]

K&N filters come precharged. If the filter is white then ithas no oil on it. If it is red, then it is charged. EVERY display I have seen the filter is charged. Just the idea that it would have less air flow is blatant false advertising and I am sure they would have been sued already. I think they didn't want you to double charge the filter.