15W40 CK4 Heavy Duty 6 x 1 Gallon

The 15W40 CK4 Heavy Duty 6 x 1 Gallon from EXTREME RACING OIL is engineered for serious diesel and heavy-duty gasoline engine applications where robust film strength and extended drain intervals are non-negotiable. This six-gallon bulk package is purpose-built for fleet maintenance, commercial truck operations, and dedicated enthusiasts who demand consistent protection across multiple service intervals. Heavy-duty 15W40 formulations like this are the industry standard for vehicles operating under sustained load, high-temperature conditions, or extended service schedules.

CK4 classification ensures compliance with the American Petroleum Institute's latest diesel engine oil standards, delivering enhanced oxidation stability, improved soot handling, and superior aeration control compared to older CI-4 formulations. The 15-weight cold-pour viscosity guarantees reliable cold-start flow in winter conditions, while the 40-weight hot viscosity maintains a protective film layer under sustained high-temperature operation—critical for turbocharged diesel engines, heavy construction equipment, and modified performance applications. EXTREME RACING OIL's proprietary additive package provides anti-wear protection, rust and corrosion inhibition, and detergent properties that keep combustion deposits in suspension, preventing sludge buildup and extending engine life.

This six-pack format is ideal for commercial operators, maintenance shops, and private fleet owners who require reliable bulk supply without constant reordering. Modern diesel trucks, agricultural equipment, marine engines, and industrial generators all benefit from CK4 protection—particularly in moderate to high-mileage vehicles where deposit control and thermal stability prevent accelerated wear. Verify your equipment's owner manual for API CK4 compatibility before use; most current-generation heavy-duty engines manufactured after 2016 are specifically approved for this classification.