The OE’s have an excellent air intake/filter system....andI would avoid oil impregnatedfilters. While they have their purposein off-road applications, Ford/GM/Dodge all have “watch-out” bulletins wherethe oil has contaminated intake sensors. - they even have a training video forthe techs on this (flatratetech.com). If you look at the flow data, WIXHP filters flow 98+% of K&N and have a much smoother flow post filter plusexcellent filtering, for a fraction of the price!
Testand Corporation conducted anISO standards test on automotive air filters which can be viewed at this link: http://www.dieselbombers.com/chevrolet-diesel-tech-articles/16611-duramax-air-filter-testing.html
“After only 24 minutes the K&Nhad accumulated 221gms of dirt but passed 7.0gms. Compared to the AC, theK&N “plugged up” nearly 3 times faster, passed 18 times more dirt andcaptured 37% less dirt.” A Ford MasterTech made this videowhich talks directly about the aftermarket CAI’s....and although you are just looking at a replacement filter, he talks about oil contamination as well. Specific to K&N's million mile warranty...that is a joke and here is my own personal OASIS documented experience with K&N.... I installed an oemreplacement unit on our new 1997 Cougar Sport (1 week old, factory specialorder), the filter was purchased directly from K&N. For those who may notknow, the Cougar Sport is essentially a mustang GT with 4-wheel independentsuspension except it is built on the MN12 chassis (LSC Coupe) which gives extrastiffness. Within 90 days, multiple intake location specific sensors(paraphrasing here) went bad...throwing codes. After Ford verified and replacedunder warranty twice the sensors during this period, when they analyized theparts, they determined oil residue from the K&N caused the componentfailure. Ford recommended the filter (K&N) be removed...and there has beenno other failures to date (2017) on these components (21 years later). I called K&N andadvised them (very nicely) of the issue....back then the K&N filter wasaround $60 iirr......they stated if you are not happy with the filter and havethe original box we will take it back and refund the $. Even with fulldocumentation, K&N never (including multiple visits with theirstaff at their offices and at conference meetings) would ever takeany action and just kept insisting there must be another cause for this withthe car...there wasn't. K&N has made repeated references throughout theyears on multiple chat sites that this situation has never occurred, yet theoasis documentation is very well established. IMHO...for filters....Napa Gold, Wix,, etc are excellent! and yes, you let that fine dirt in....it will certainly impact the longetivity of the turbo impellors.