I have an 03 WR 450 and it has been sucking dirt passed the filter some where. There is a thin layer of dust in the boot between the air filter and the carb after dusty conditions such as a desert race, but also sometimes just trail riding. I have tried everything I could think of. -First I was told not to use no toil. I tried maxima fft and there was no difference. Same thin layer of dust on boot passed filter. - I have had three different filters, No Toil, Uni, and stock Yamaha. - Next I was told I was not greasing the filter rim enough. I put about an 1/8 Inch layer of grease on the filter rim and I got the same thin layer of dust. - I have also never seen any signs of dirt on the inside of the filter. I would think if it was coming through the filter oil I would se it on the inside of the filter. - I have taken apart the air box three times now and sealed the spots where I thought it could be coming through with Yamabond. It sure seems sealed tight to me, but dirt is still coming through some where. If anyone has seen this happening and/or just has any ideas please reply. Thank you very much Drey I have photos , but was not sure how to upload.