What is the difference in using KI & N air filters?
In my opinion, next to nothing. I don’t think they can help the mpgs, regardless of ads, because they are upstream of the throttle. Possibly they might give a little extra hp at wide open throttle. Do they hurt? No, but I have no interest in cleaning oiling etc. I just put on a new Fram.
In general they offer less air resistance (possible more power at full throttle) maybe a tiny increase in mileage and you will not need to buy new ones on a regular basis. However there are some down sides. They don’t really filter as well as even the cheapest paper (OEM type) filters and if you are not really careful when re-oiling the filter you can damage MAF’s or some other parts of a modern engine.
I did have one a a car some years ago and decided to dump it once I found out what they are all about.
Are we talking about K&N filters that fit into the same housing as the stock paper filter? If so, stick with the paper filter. If we are talking about one that replaces the stock air filter housing so you can mount a cone shaped filter, you might see a boost in horsepower and a drop on fuel economy. If you know how to clean and oil a K&N filter, you might find it adequate, but in my opinion it is easier just to spend $12 on a paper filter.
Amen. Some of the guys at bobistheoilguy.com who used K&Ns have gotten rid of them, after getting a couple of used oil analyses showing increased silicon (dirt) levels. That convinced me the higher cost of the K&N would not worth it, regardless of power increase.
One problem I have seen with using the K&N filters is that over zealous oiling of the element can contaminate the MAF sensor wires. In some cases, the MAF cannot be cleaned after it goes through multiple decontamination cycles and must be replaced.
I remember a Nissan TBS that dictated replacing the MAF sensor and returning to the OEM airfilter to correct a driveability problem.