CITGO's CITGARD 600 Multi-Viscosity Engine Oils protect current and older model low-emissions engines equipped with exhaust aftertreatment systems and other new design features. These products exceed the API CJ-4 heavy duty requirements as well as existing API CI-4 PLUS and earlier categories. Recommended for use in heavy-duty service in commercial trucks and other diesel-fueled engine applications, these oils permit year-round use by offering improved low-temperature startability with full lubrication at high operating temperatures.