Personally, I do put a very light coating of oil on it just to help catch any dirt but be careful not to overdo it and prevent air flow.
I don't think you're going to prevent air flow to the air jet solenoids. On both 1500s that I've had the sub air filter box off, the top and bottom halves of box don't seal and air is drawn in through the gap between the halves instead of through the filter material in the bottom, below the gap. I think this a crappy design. They would filter better if the medium was in the larger top half of the filter box instead of the bottom. Maybe not all 1500s leak air in between the halves but the two I've had experience with did.