I changed my XJR's AC Delco air filter after only 10K miles and was surprised how much dirt was between the pleats when I bent the filter. It runs fine so hopefully this is a good sign that the dirt isn't getting into the engine. Is this common? I don't remember previous cars' filters looking that dirty.

 

Exactly the purpose of the filter. Depending on where you live, it can be more or less.

Now, consider that you get a free flowong filter from say K&N. The ***** you found today would not be there, bdcause it would be in the engine. Same goes for sand. I live in a very dusty area, even though wet. When dry, the ground is easily turned to a dusty sandy air. My air filter box is always FULL of sand when I change the filter. My brother's Passat with a K&N filter is always spotless inside... Even though he lives in the exact same area and drives as much as I do.

People believe the K&N crud will increase flow without sacrificing air cleaning... I call out BS. Air flow is increase by dropping filtration. That is the only way it works.

But back to your filter... It did the job just right then!

 

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