Duralec Ultra combines premium base oils with Royal Purple's proprietary additive technology, Synerlec, to create a high-performance motor oil that optimizes engine performance and provides superior protection in rigorous on/off highway applications. Synerlec provides unsurpassed film strength and lubricity – up to 4X more than top competitors. In addition, advanced synthetic solvency reduces engine deposits and keeps engines clean. The net result is a better performing engine, with reduced downtime and lower cost of ownership. Royal Purple recommends for use in a variety of heavy-duty applications including commuting, over-the-road trucking, agriculture, construction and mining.