The Stovebolt Site Forums The Shop Area Engine Shop Wet vs. Dry Air Filter

I switched to a dry element because, in my opinion, it filters better. As you can see above there are differing opinions. My reasoning:
1. Dry elements filter particles measuring in microns.
2. The copper mesh in the oil bath filter has pathways large enough to let particles 100 times larger through.
3. While the incoming air gets pulled through the oil before going through the mesh that doesn't necessarily trap the dirt because the air goes through as bubbles. Each bubble could harbor damaging dirt particles that are small enough to pass through the mesh.

Assuming Dusty is correct about trucks affected by the Mt. St. Helens incident. I believe the paper filters did their job by preventing ash from entering the engines. The oil bath trucks obviously let the ash through or they would have plugged too.