N9LO said:
It lowers air flow restriction like a free flowing exhaust helps. I've been using the drop in for many years, first in my old Yukon. If you clean it and then over oil it you would be the idiot causing your own problem. The oil on the filter is minimal and has never caused me any problems. That is why I use them. Remember the foam air filter on a lawn mower? You wash it, dry it, and load it down with oil. Did it hurt the valves? No. Mechanics use this K&N myth because they are no longer selling you paper air filters and scam their money selling you a mass airflow sensor because there is no way for you to tell if it id bad or not. If it was true they would be sued so much.
http://www.knfilters.com/MAF/massair.htm http://www.knfilters.com/news/news.aspx?id=422
Ok then explain how it caused the issues when it CAME in the truck(I haven't re oiled nether filter)
There is a thread on here that explains the whole thing and the k&n drop in filters faired the worst in a lab test which compared it to many different filters including the oem gm filter(which out did the rest in every way)
In my truck it kept messing with the mass air flow sensor and making it throw a performance code
In my mom's 02 it messed it up to where it was making the 02 sensors throw codes along with the mass air flow sensor throwing the same code
Since I swapped them out for gm filters the problems went away and both trucks run BETTER then they did with the k&n filters
I never did anything to either filter as they both looked clean(despite living on a dirt road)
Gm put more money into r&d on the stock air box then you think to get it to work with the engine with the gm filter
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Btw a lawn mower engine doesn't see the environment a car or truck engine does
Besides I never oiled the filter on my go cart engine when I first put it into service as it has a two stage filter and doesn't need oil in the filter
Has yet to give me trouble