Staff Answer
Sep 23, 2026 - 11:33 AM
Our newer Sinister Diesel Universal Replacement Reusable Air Filters (4" Inner Diameter) feature a convenient "dry" or "oiled" label on the collar near the clamp, making it simple to identify your diesel air filter type. However, older 4" air filters do not include this marking. If you purchased your 4 air filter directly from us, please refer to your original order details, as the filter type should be indicated there.
