PennGrade® Heavy Duty is a new generation of diesel engine protection. Advances in diesel engine technology have escalated significantly from what existed a decade ago. Today’s engines are substantially more powerful and efficient than once imagined. Changes made to achieve this have created more severe operating conditions that place new levels and types of stress on the engine oil. In response to this, the lubricant industry has adopted new performance standards, designated as API CK-4. Engine oils meeting this new standard must deliver increased levels of engine protection and oil durability that meet the needs of new engine designs while simultaneously providing a higher degree of protection for older model engines. Equipment manufacturers are adopting elevated standards at the same time to meet the specific needs of their engine designs.