CITGO CITGARD 600 Engine Oils Multi-Viscosity Grade use superior technology to protect current and older model low-emissions engines equipped with exhaust after-treatment 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, agricultural equipment, construction equipment, stationary engines, and other diesel-fueled engine applications. Permits year-round use by offering improved low temperature startability with full lubrication at high operating temperatures.