I run the Belray waterproof grease on the bottom and top seal of my filters as well as the cage screw. It's supposed to be linkage grease for shock linkages. It's like $12 a dish or so, kind of expensive, but I've barely used any so far and I use it on everything including diff orings, driveshafts and I've even used it to stop an air leak around a carb slide now.
Best part about it, it guarantees not to swell Orings and is waterproof.
I also use MC1 oils on my filters. Lots of things carry over from my old motocross days...