My son use to have an 04 Impala; we did UOA. K&N air filter had like hundreds of ppm silicon. (I think 20ppm is max per Blackstone or Horizon testing on a "healthy" engine). http://www.ppmoiltesting.com/eval1.html Only change we made was getting rid of K&N air filter and silicon ppm dropped to normal. K&N air filters may have their place on Baja vehicles, but not for street use. If someone gave me a K&N air filter for use on my car today it would go in the trash.K&N filters don't ever get that dirty...because they pass all of the dirt and debris right on through to the motor.