The Hot Shot's Secret 15W-40 Synthetic Engine Oil from Lubrication Specialties offers a unique blend infused with FR3 Nano Technology and a CK-4 additive package to improve mileage and performance. It was developed specifically for severe duty fleets hauling heavy loads, stop and go deliveries, or operations where there are a high level of airborne particulates. The engine oil is part of the company's Green Diamond Fleet line of diesel oils.