Motor Oils
Heavy-Duty Motor Oils
Premium heavy-duty diesel engine oils from Petro-Canada DURON™ and Phillips 66 GUARDOL®. API CK-4 and FA-4 licensed oils engineered for maximum protection, extended drain intervals, and fuel economy in on and off-highway fleets and equipment.
A New Heavy-Duty Engine Oil Standard Is Coming: PC-12
PC-12(Proposed Category 12) is the next generation of API heavy-duty diesel engine oil standards, developed to meet the U.S. EPA's 2027 emission regulations that call for a 75% reduction in NOx and a 50% reduction in particulate matter. It builds directly on the current API CK-4 and API FA-4 categories introduced in 2016.
Like today's standard, PC-12 will be split into two subcategories. The backward-compatible category, CL-4, succeeds CK-4 for use across existing and new engines, while the fuel-economy category, FB-4, succeeds FA-4 for lower-viscosity applications. Both are engineered for improved fuel efficiency, enhanced wear protection, extended oil drain intervals, and longer aftertreatment (DPF/SCR) system life. First licensing is anticipated January 1, 2027, aligning with Model Year 2027 engines.
Better Protection
Advanced wear control and oxidation stability protect modern engines and aftertreatment systems.
Improved Fuel Economy
Lower-viscosity FB-4 options improve fuel efficiency without compromising engine durability.
Extended Oil Life
Enhanced oxidation control enables longer oil drain intervals, reducing maintenance and downtime.
Heavy-Duty Diesel Engine Oils
Premium protection for on and off-highway diesel engines
DURON™ Product Line
The Tougher. The Better.
DURON™ UHP
Ultra High Performance synthetic engine oils give you ultimate protection and extended drain intervals in the most demanding conditions.
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DURON™ SHP
Super High Performance synthetic blend engine oils offer excellent protection with outstanding value for mixed fleet operations.
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DURON™ HP
High Performance engine oil delivers on performance with proven protection for on and off-highway diesel engines.
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DURON™ Advanced
A fuel saving oil for advanced heavy-duty diesel engines, designed to maximize fuel economy without compromising protection.
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DURON™ GEO
Specially formulated for the high combustion temperatures in today's natural gas mobile engines. Also provides premium performance for heavy-duty diesel and gasoline engines.
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DURON™ Monograde
Monograde engine oils for a wide range of heavy-duty service, fueled by diesel, gasoline, propane, or CNG. Proven in mining, construction, and agriculture with excellent anti-wear and thermal strength.
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GUARDOL® Product Line
The Science of Performance
GUARDOL ECT®
GUARDOL ECT® Synthetic Blend Diesel Engine Oil
Emission Compatible Technology synthetic blend diesel engine oil providing premium protection for modern diesel engines with advanced emission systems.
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GUARDOL XT®
GUARDOL XT® Full Synthetic Diesel Engine Oil
A premium full-synthetic diesel engine oil engineered for maximum protection, fuel economy, and performance in the most demanding heavy-duty applications.
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GUARDOL FE®
GUARDOL FE® Synthetic Blend Diesel Engine Oil
Fuel Economy synthetic blend diesel engine oil formulated to improve fuel efficiency while maintaining durable engine protection for mixed fleets.
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GUARDOL Fleet EC®
GUARDOL Fleet EC® Diesel Engine Oil
Emission Compatible synthetic blend API CK-4 engine oil designed for mixed fleets operating under varying conditions.
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GUARDOL® NG-D
GUARDOL® NG-D Natural Gas Engine Oil
High-quality synthetic blend engine oil designed for natural gas engines in heavy-duty transportation and stationary applications.
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Need Help Choosing the Right Diesel Engine Oil?
Our technical experts can help you select the optimal heavy-duty motor oil for your specific fleet, equipment, and operating conditions.