Engine air filter "prefilter"

[RandyCSVT]

Just changed my air filter after 30k miles (surprisingly my filter minder I installed in the top half (post filter) of the airbox showed little to no restriction 30k miles later). I noticed the prefilter looked a bit dirty. I vacuumed it for good measure, but is this thing even a serviceable part of the vehicle or should I just leave it alone and be happy with a new air filter?

The old filter was a bit dirty after 30k miles, but cleaner than

I expected. This filter is huge, so I assume it takes a pretty soiled filter for any restriction of air flow.

 

[JZelnick]

I vacuum the air box and the prefilter during each filter change. Sometimes a little mud will find it’s way in the bottom of the box, so I clean that up with a rag and all purpose cleaner.

 

[RandyCSVT]

I did the same