Mag 1, QT, 15W40 Diesel Oil, High Detergency & Superior Dispersancy Keep Engines Clean & Soot Suspended In The Oil Despite Longer Drain Intervals & Increased Soot Loading, Exceptional Resistance To Thermal Degradation, Even Under The Most Severe Operating Temperatures, Prevents Viscosity Increase & The Deposit Formation & Wear That Can Result, Superior Anti-Wear Agents Extend Engine Life Despite High Operating Temperatures & Extended Service Intervals, Higher Starting TBN Provides Added Protection Against Acid Build-Up That Can Cause Rust & Corrosion, Highly Reliable Performance Over A Wide Range Of Temperatures, Including Severe Cold.