The internet is awash with contradictory advice on whether or not its better to retain the factory foam oil rings that sit beneath the dust seals on various forks. Well here's my take - foam rings, regularly cleaned or replaced and properly soaked in oil are a fantastic thing.
- keep the stanchions, seals and upper bushings well lubricated and this translates into a plusher, more responsive fork;
- provide a secondary line of defence between your dust seals and bushings. Once you get dirt down into the bushings your fork stanchions will last all of 5 minutes.
Sure they get dirty, but this is exactly what they are supposed to do. They get dirty and keep your fork insides (and particularly your bushings) clean. If you don't use the foam rings, then the dirt normally trapped in them is now inside your fork.