About Signature Series 15W-40 Max-Duty Diesel Oil
Signature Series Max-Duty 15W-40 is a diesel-engine oil to compare for your truck or equipment. Keep the engine’s manufacturer requirements at the center of your choice, especially when evaluating different viscosities or service conditions.
Before you choose
Confirm the permitted 15W-40 viscosity, required diesel-oil performance category, and any OEM specification. Check model-year and emissions-equipment requirements before using this product.
Does towing change how I should plan oil service?
Your manufacturer may classify towing or other demanding use as severe service. Review that schedule and AMSOIL’s current application and service guidance before extending an interval.
Product information reviewed September 7, 2026. Read AMSOIL’s current specifications.
