Mobil Delvac Extreme 15W-40 is a high-performance synthetic diesel engine oil that helps to deliver extended performance for up to two times beyond OEM recommended oil drain intervals* for modern diesel engines operating in extreme conditions. Mobil Delvac Extreme 15W-40 is recommended for use in a wide range of heavy-duty applications and operating environments found on- and off-highway conditions, including engines operating under heavy loads. Fully backward compatible, it delivers excellent performance in both newer and older heavy-duty engines, meeting or exceeding the requirements of API CK-4, CJ-4, CI-4 PLUS, CI-4, and other service categories. This diesel engine oil provides exceptional high temperature performance, oxidation stability**, and resistance to corrosive and abrasive wear to help promote long life of critical wear surfaces. Mobil Delvac Extreme 15W-40 also offers excellent low-temperature performance for increased oil flow to critical bearing surfaces at startup, controlling fluidity and pumpability for smooth starting in cold weather. (*Results may vary based on vehicle/engine condition, driving and environmental conditions Consult OEM or ExxonMobil before implementing extended ODIs. ** Based on the performance in the Volvo T-13 engine test.)