Ok. I put the AFE CAI on my truck without a single issue and yes, it's an oiled filter. No CEL, no issues with how the truck runs, but certainly notable improvements. After the AFE headers, mid-pipe and exhaust were installed, I was about 600 miles in and the CEL illuminated. I scanned my truck and pulled a P0420 code, which relates to an issue on Bank 1 Catalytic Converter (passenger side). I cleared the code and have since put another 800 miles on the truck and the CEL has not illuminated again; I doubt seriously that it will. The truck seems to run better and better every day.
Bottom line is, installing a CAI isn't a big deal. Have the code cleared and rock on. For those saying it causes nothing but issues, blah, blah, blah; don't be so scared. I've done 99% of the upgrades to my truck myself and success boils down to educating yourself properly. Living scared is living scared. Dive in and learn something new....
Last thing, a CAI isn't a component or system that buys anyone anything all by itself. It's part of a bigger system so if you're looking for big gains with plans of only doing a CAI, don't bother. Will the engine sound a little better and will you notice small differences? I did on my truck. My point is, unless you have plans to do more induction upgrades beyond the CAI, keep your stock CAI. If you have plans to do intake, heads and exhaust system upgrades, a CAI is a great place to start but don't stop there. But in your case, is having a CAI by itself a big deal? Will it cause nothing but problems? No. Just clear the code and go from there.
Stop being so scared....
MB