This one filter has done the job in my 2001 Silverado for 13 years and 225,000 miles. I have never had the heads off, so I cannot comment on the condition of the cylinder walls. Does not burn oil and still runs great. I have not cleaned it as often as I should have. Have only cleaned it 2 times. So counting it being clean when installed, it's been without dirt 3 times in 225,000 miles. No evidence that any dirt ever got through it. Use the K&N cleaner and no other cleaners. Do not use hot water as it can shrink the cotton fibers making the filter look wavy. All of the dirt will wash out with ease. Let dry, I sit mine in front of a fan. Recoat with the K&N oil which is red so you can see that you have fully covered it. Put a thin coat of K&N grease on the neoprene seal and you are ready again. This filter maintains it low restriction to air flow, even when very dirty. I have these in all of my vehicles, not to save money, but because they stop dirt better and allow more air flow. Cars that sit outside sometimes attract mice that chew up the paper air filter and make a nest. Not possible with the oil soaked K&N.