The 06 C350 I've got now is on the original filters (yes,2, one on each side). It has been on the road for close to 3 years. They're a little dark, but the car has 28k miles and the manual calls for every 60k or 5 years if I am not mistaken. Now, on my 202, I was replacing them every 10k; they were cheap online, and clean filters are good, right?

I just feel like it's probably not necessary. When are these OEM filters truly in need of replacement?

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former: 83 300D, 97 C230, 93 400E

current: 08 C300 Luxury , 92 500SL