[Fulltiming]

My Detroit Diesel 8V92 uses a 50 micron primary filter and a 20 micron secondary filter. In a two filter system much of the dissolved asphaltenes (distillation residue having asphalt-like properties) in the diesel are caught by the primary filter, resulting in a secondary filter that is relatively clean and better able to remove fine particles. A two filter system can last longer and result in better debris removal than a single fuel filter system. In your system the first filter is a combination primary filter and water separator. Without a separate water separator, I would be leary of using a single fuel filter.