My Focus come with one of those "lifetime" air filters from the factory. It had something to do with emissions and the PZEV regulations. Anyhow, when I bought the car I removed the factory air filter box and tubing and clamped on a Spectre air filter. Basically just a factory intake with a cone-style filter on the end; a cheap and effective CAI, and a very popular mod on the Focus forums. Anyhow, the filter itself is tucked up nicely behind the driver's side splash guard, and is barely visible when you look through the lower grille (although if you look hard, you can see a little bit of it). I'm thinking that every now and again, dust/water spray can find its way through the grille and right to the filter media... Which leads to me wondering if I should buy the $10 oiling kit, or just spend $20 on a new filter? The filter is pretty nicely tucked away, yet it's still exposed, meaning that it probably takes a decent amount of abuse. Knowing how I over-do everything, I'd probably end up over-oiling the filter anyhow. Should I just buy a new filter and forget about it? I plan on replacing the filter and cleaning the MAF every 20,000 miles.