Mobil Delvac Extreme motor oil is a premium synthetic blend, high-performance diesel engine oil. It helps extend engine life, while providing long drain capability for modern diesel engines operating in extreme conditions. Delvac Extreme is recommended for use in a wide range of heavy-duty applications and operating environments found on- and off-highway, including engines operating under heavy loads. Fully backward compatible, this oil delivers exceptional performance in both newer and older heavy-duty engines. It delivers updated high-temperature performance under the extreme operating environments found in the trucking, mining, construction, and agricultural industries.