PSO DEO MAX (15W-40)-4L is a high-performance heavy-duty engine oil engineered to provide exceptional protection and durability for modern diesel engines under tough operating conditions. It meets the API CK-4 service category, offering superior wear control, thermal stability, and soot handling for extended engine life. Designed to maintain strong oil film strength and protect against oxidation and deposits, this oil helps ensure reliable performance even in high-load and high-temperature environments.