I have 94 F-150 with 4.9l six cylinder and it has stock replacement type K&N air filter.My question is does anybody have any problem with K&N filters letting dirt through? I live in arizona and it gets windy and dusty sometimes,I`m thinking maybe I should go back to paper filters.Anybody have higher silicon in their oil analysis from using K&N filters? I use a good oil filter to give me a little insurance.

 

I believe the K&N's do let more fine dirt through. This probably won't be significant, however, unless you plan on running the truck for well over 100,000 miles.

If you agree with me, you should realize that some damage (throttle body, heads, injectors, valves, seals, rings, cylinder walls, etc.) could have been done before the oil filter sees the dirt. In fact, I would expect most of it to flow through and out the exhaust.

Others on this board (and elsewhere) disagree with me on this. I cannot prove my opinion.

MrBSS

 

I have just cleaned my K&N air filter on the Aerostar for the first time at the recommended 25,000 miles. Most of the mileage was in desert states, and a few sandstorms, but not off-road. The Aerostar has a long pleated pipe between the filter box and the manifold (ideal for collecting dust), and there was no dust in that. After cleaning, when held up to the light I did notice a few lighter spots in the filter element - perhaps nascent holes. K&N says their filter will last for 1,000,000 miles or 40 cleanings. I don't believe it, even though there is an ad for them at the top of this page. But for now, I'm happy with the filter. Haven't done an oil analysis. Some Fords had (still have?) pistons made from an Al-Si alloy (because of its low coefficient of expansion). That can be a cause of high Si in the oil. Jan Richter

 

i live in tucson, az and i cleaned the K&N in my honda accord at only 7000 miles on the filter. i noticed a light coating of fine az dust downstream in the airbox and pipe. i cleaned the filter then oiled the heck out of it. i cringe to think of what my throttle body looks like (from dirt and extra filter oil). i also tried k&n in a volvo and an infiniti. i think the performance improvement is more psychological than substance. i'm buying my first f150 (99 4.2 5sp). has anyone used the k&n in this truck with definite positive results? let me know.

 

K&N does offer an air filter wrap that they call the "Pre-charger" That is supposed to be used in very dusty conditions. Some type of polyester & elastic hood. I know they are made for all of the cone type K&N's but I'm not sure about original equip. style.

 

After getting my first oil test results back, I know better than to run a K&N without that pre-wrap. It's funny, I don't even use the K&N anymore, I use a paper filter with the prewrap. There's no point in risking engine damage for 1/10 HP. Honestly, there is no performance benefit that you'll be able to feel, and it sure won't make a difference in your gas milage. I had a very high silica count in my oil, that's when I decided to quit fooling around with those things. I tried hard to feel that extra power, as would anybody who spent $40 on an air filter, but it just isn't there. Go buy a couple cases of beer with that $40, you'll get more out of it, and it won't ruin your motor, well, unless you try to drive it after all that beer. TK

'77 F100, 302 (the aftermarket Prodigy), C4
Cadet Second Lieutenant John F. Daly III
South Carolina Corps of Cadets, The Citadel
The TorqueKing

 

I think I agree TorqueKing,I may just go back to using a purolator paper filter unless there is a precharger for my application which is a stock type for 4.9L six. What about oiled foam? does anybody use those? do they shed too much oil?

 

I like the K&N filters but I won't run one without the pre-charger wrap. It not only filters down to, I believe 5 microns, it's also great added protection from wtr getting into the intake.

 

I know this is a little off subject, but I convinced my father to run a K/N filter in his 97 Tacoma. Well, he is absolutely precise on measuring his gas mileage at every fill up and during the winter he drives the same route on a day to day basis. Well, he was not impressed with it to say the least. No change in mpg and no change in "power" as K/N suggests. I'm not impressed with these overpriced filters! I'll stick with paper.

 

Yeah but that K&N impresses all the women-folk when I open my hood!!!

The story is the same with K&N filters as it is with women; it is always best to "wrap" it or you could risk damaging your internals...uh...engine internals...

 

 

Here's an article on air filter tests using SAE J726 standards. The only bad part was they used a Fram filter for the paper element. They also tested K&N and a foam filter. Interesting reading.....

Reggie

 

I must be brain dead lately.....

Here's the article:

http://www.ducatigarage.netfirms.com/filtertest.html

Reggie

 

i installed the k&n filter on my 351, the exhaust sounded cleaner, the engine sounded cleaner, there was def. a noticeable increase in throttle. its the driver and environment that lets dirt into the engine, its not just because of the filter. i am happy with the K&n and will buy another one when i have to. if you are that worried about letting dirt into the engine do not drive the truck offroad or in dry areas. its just part of the engine wear and theres nothing you can do to stop it, all you can do is slow the process down. just my 2 cents.

 

The debate goes on. I was running a K&N filter in my truck for a couple of years. I just went back to a paper element to get a baseline (I didn't want the air filter to be an unknown variable) on some oil samples I'm running to see if their is any difference between Motorcraft FL-1A and Purolator Pure One oil filter. When I switched back to the paper I noticed no difference in performance or MPG. We'll see, maybe I'll put the K&N back in and run a few more oil samples after I'm done playing with oil filters. If I still have the truck by then. That new F-350 with the 6.0L diesel has been in my dreams for a while now. I may have to make that dream come true pretty soon.