Doc's Diesel 15W-40 Full Synthetic Heavy Duty Diesel Oil – 3 Gallons | DOCS15W40-3

Engineered for today’s hard-working diesel engines

Doc's Diesel 15W-40 Full Synthetic Heavy Duty Diesel Oil is built to perform across a spectrum of engines—from modern emissions-compliant rigs to reliable older workhorses. The oil delivers a smooth, protective feel in the crankcase and maintains strong flow during cold starts, contributing to reliable protection when the motor first wakes up. Its amber hue hints at a balanced, high-quality formulation designed for durability in demanding conditions.

Why drivers and fleets choose Doc's Diesel 15W-40

In real-world use, this oil supports sustained protection under heavy loads, high temperatures, and tough environments. The formulation helps maintain dependable lubrication, reduces varnish and deposit buildup, and supports consistent engine performance across diverse operating cycles. It’s crafted to guard critical components while resisting the harsh effects of demanding service.

• Excellent low-temperature pumpability for fast lubrication during cold starts and harsh weather
• Robust oxidation and viscosity control to minimize deposits and extend oil life
• Effective protection under severe service, including towing, hot climates, and dusty environments
• Broad OEM and spec compatibility, including major API and industry standards

This product aligns with broader emissions considerations, with design elements that may contribute to cleaner operation and potential fuel economy benefits in some fleets. It’s formulated to meet contemporary needs while remaining suitable for older diesel engines that still demand strong protection and reliability.

Specifications, compatibility, and usage guidance

• Meets API CJ-4/CK-4; SN and backwards compatibility with several older classifications
• Approvals and compatibility include Cummins CES 20086, Mack EOS 4.5, Volvo VDS-4.5, Renault VI RLD-4, Renault VI RLD-4, MB 228.31/228.51, and others
• Designed to resist thermal breakdown and reduce deposits under high-load, high-heat conditions
• Maintenance intervals vary by service level: normal service typically 10,000–15,000 miles; severe service 7,500–10,000 miles; off-road 250–500 hours, following manufacturer guidance

Doc's Auto Parts also offers a full line of replacement filters and maintenance essentials, designed to complement this diesel oil and support a comprehensive care routine for your fleet or personal diesel vehicle. This 3-gallon container is built for convenient handling and steady availability in both fleet and shop settings.