Royal Purple Duralec Ultra Motor Oil is speciﬁcally formulated to maximize performance and meet the demands of today’s heavy-duty diesel 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 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 motor oil is recommended for use in both two-cycle and four-cycle diesel applications including automotive, commercial ﬂeet and stationary industrial diesel engines.