I would make sure you are using a filter with an anti drain back valve in it. I always run Napa gold filters in my 4.0's because the anti drain back valve helps keep some oil in the top of the motor. I also use Mobil 1 High Mileage oil in them too, no mater what the mileage is on the motor. The Mobil 1 High Mileage has additives, (Zinc I believe) in it to help the flat lifters in the 4.0 live longer and run quieter. I have replaced the lifters in an 03 and an 04 Rubicon, because I didn't like the noise. It went away, but it cost a lot of $. As some of the other posters have said. It will probably run forever, but it will be noisy. As an alternative, you could always install a better radio...Good luck with the noise, as I hate it too. Now with the economy getting better I just store the Jeep in the winter and bounce the old Explorer off the snow banks in the winter...ahhh the lap of luxury.