I do not agree with that price comparison one bit. The K&N drop in filter for my car was only $34 at the Zone and a cleaning kit is only $12. The cleaning kit is good for at least 4 cleanings(if it doesn't, you're over oiling). Assuming you live in a dirty climate where you actually do need 25k cleanings, you're still at only $46 for 5 years. That's $9.20(not 18.73)/yr compared to Amsoil's $9.53/yr filter.

And how does no filter end up testing worse than OEM style?

I wondered that too. Aerodynamic concern, maybe? Perhaps the filter straightens out the flow which gets turbulent sans filter....or just that not enough tests were done and there was one bad test on the one no filter try.

Also, .8 micron = 0.0008 millimeters.

The smallest grains of sand are around .02mm. By the time something is .00Xmm in size you are looking at very small dust particles. These are obviously airborne and aren't going to just fall into the cylinder and build up. They will readily burn and get expelled out the exhaust port. Efficiency at .8 microns shouldn't impress. Oil getting past the rings and carbon build up breaking loose in the combustion chamber has much larger particles in it. (Most automotive engine oil filters are only rated to 8-10 microns)

Additionally, I've never heard of an engine with a K&N, or any filter for that matter, fail from poor filtration quality. Over oiling mucking up sensors yes, but that can happen from any wet filter.

I did a T test at https://www.graphpad.com/quickcalcs/ttest1.cfm

The result was no significant difference between OEM and K&N at the 95% confidence interval. But then again- the sample sizes are tiny.

Results below:

Paired t test results
P value and statistical significance:
The two-tailed P value equals 0.0577
By conventional criteria, this difference is considered to be not quite statistically significant.

Confidence interval:
The mean of KN minus OEM equals -0.5500
95% confidence interval of this difference: From -1.1853 to 0.0853

Intermediate values used in calculations:
t = 11.0000
df = 1
standard error of difference = 0.050

Learn more:

GraphPad's web site includes portions of the manual for GraphPad Prism that can help you learn statistics. First, review the meaning of P values and confidence intervals. Next check whether you chose an appropriate test. Then learn how to interpret results from an unpaired or paired t test. These links include GraphPad's popular analysis checklists.

Review your data:
Group KN OEM
Mean 70.6750 71.1750
SD 0.2784 0.0354
SEM 0.1392 0.0250
N 4 2

I think there's a reason Detroit abandoned the use of oiled filters over 50 years ago. People weren't maintaining them properly. The paper throwaway filters are much better - there's no oil residue to muck up the environment.

You can't argue with that ping pong ball display unit K&N has though. lol

Well, if I ever have the need to put ping pong balls in my air intake I will make sure to put a K&N filter on the vehicle first... ;)

LOL........why not......don't you want a car with balls??......LOL

^^^ ok....sorry I got a little OT.

After reading all that stuff, I don't feel good about useing any of the aftermarket air filters, K&N included so I don't think they are worth the money.......I am just useing the standard paper OEM type ones.

The paper ones last so long now. I replaced the paper one on my truck this summer, not because of mileage (~45,000 miles) or because the indicator was showing it was worn out (the air pressure indicator was still showing it was good), but because it was 4 years old and it was only $15 to replace.

-Jay