Best advice I can give is find some good dirt bike air filter oil. I use Bel-Ray oil. Clean your stock filters (I mean the brand new ones or the old dirty ones) and re-oil with said good quality dirt bike oil. I change my filters often and will change them more than once per day if it's really dusty at the track.
I found the oil that comes on the losi filters is way to thin for my taste. I cleaned them before I ever ran the car. Don't know what they use but it's not put on thick enough for me.
If you can find it, PJ1 makes a great air filter cleaning product to get all the old crap out of them. Twin Air also makes a good cleaning fluid for foam air filters.
As to what Homer said above you can do what we do with dirt bikes and add a small bead of grease to each end of your filter to seal the ends. I haven't done it yet with my 8ight but I used to do just that with my old Mugens