Originally posted by drees
Keep in mind that a dirty air filter will filter out more dirt than a clean air filter.
That applies to K&N type filters, but I don't think paper ones since they don't rely on oil for filtration and have smaller passageways.
I changed mine at 10K miles because of the fires too (otherwise I would've done it later), and some sections had a black, sooty residue.
I just use the Purolater ones from Pep Boys, pretty cheap and high-quality.