West Marine Premium Heavy-Duty 4-Cycle Engine Oil exceeds OEM requirements and will not void engine warranties.Recommended for engines requiring API CF-2 level performance,our Premium Heavy-Duty 4-Cycle Engine Oil exceeds warranty requirements for all diesel and gasoline engines specifying SAE 30 or SAE 40 grade and API service classifications including Caterpillar, Cummins, Detroit Diesel, Mack, Navistar, Volvo and Mann. Heavy-duty formulation minimizes engine wear for long engine life.Key FeaturesWill not void engine warrantyRecommended for engines requiring API CF-2 level performanceHeavy-duty formulation minimizes engine wearSpecificationsAPI Service Classifications:CF-2, CD-II, CD, CF, CE/SJ, SH and SGExceeds:Mack EO-K/2 and Allison C4 specifications and CID A-A-52306A requirementsDecoding Engine OilEver wonder what API service classification codes really mean You'll find answers to this question and a lot more in our West Advisor Article "DIY Changing Engine OIl on a Boat Motor". Click on the "West Advisor" tab above.