Originally Posted by garybtt
Why so negative on K&N?
Because they don't filter as well. That's what filters do...filter. K&N advertises better flow...I can beat their flow numbers by simply taking the filter out. That defeats the purpose though. K&N is a comprimise. If you drive in fairly clean conditions, great. I wouldn't use a K&N or any other cotton gauze filter on a farm or where I'm going for long term reliability. You guys that aren't keeping your vehicles for 300k+ miles aren't really affected...but the owners after you are. I would pass over a vehicle with 150k that had a dirty engine compartment and used a cotton filter.
Its an engineering fact that the TESTED (not claimed) micron rating on cotton gauze filters is much higher than paper elements filters. Larger particles are allowed through. The best way to get more flow without comprising filtration is to use a larger filter.
K&N pros and cons and the facts have been discussed ad nauseum on the net for anyone wanting to research it. Plenty of unbiased test by users have revealed poorer filtration performance.
Also, diesels are particularly sensitive to being "dusted" by a poor or failed filter. The higher compression increases the force on the rings and creates premature wear and failure in the presence of dirt.
If you are racing, K&N is great. (In fact, no filtration is best) If you are looking for MPG gains...K&N is selling snake oil. If you want maximum durability, paper is best. It just depends on what you want AND knowing the facts before you choose.
---------- Post added at 02:27 PM ---------- Previous post was at 02:02 PM ----------
Originally Posted by MuSh
I've used K&N all my life. Motorcycles, vehicles both gas and diesel.
Denied warranties: 0
Ruined engines: 0
How many warranties and engines have you had ruined by a particular air filter brand? I'm willing to bet that number is zero as well.
Federal statute law says automotive companies are prohibited from requiring you to use a particular brand of service or maintenance item (e.g. Oil filters and air filters) unless they are provided to you free of charge. This goes for service providers, too.
Unless they give you free parts and free service, they cannot mandate you use a particular dealer/servicer or part brand in order to keep your warranty intact. All they can do is recommend.
If you have a dealer stating you have to see them to keep your warranty and use genuine oem parts at their astronomical dealership prices, I'd show them the law or contact a legal representative. I get the impression you're not speaking from personal experience,
If the K&N doesn't meet the filtration performance of the OEM filter, that law isn't applicable. Cotton gauze filters don't filter as well as paper. Google the diesel forums for tons of info. If K&N won't warranty a dusted motor, I'd pass since we already know they don't filter as well.
Here's an interesting read for anyone that hasn't made up their mind already.