Royal Purple Duralec Ultra 15W-40 motor oil is specifically formulated to maximize performance and meet the demands of today’s heavy-duty engines. Duralec Ultra is fortified with a high level of zinc/phosphorus anti-wear additive and Royal Purple’s proprietary Synerlec additive technology.
Synerlec creates a tenacious ionic bond with metal surfaces, providing protection upon startup and greatly increased film strength that helps eliminate metal-to-metal contact, even under severe conditions.
Duralec Ultra 15W-40 reduces parasitic loss to save fuel and its synthetic solvency keeps internal engine parts cleaner than detergents alone. Superior oxidation resistance also greatly extends drain intervals and minimizes oil degradation. Duralec Ultra 15W-40 motor oil is recommended for use in both two-cycle and four-cycle diesel applications including automotive, commercial fleet and stationary industrial diesel engines.