What kind of oil does a Ram 3500 6.7 diesel take?
The Ram 3500 with the 6.7-liter Cummins diesel generally needs a full-synthetic diesel engine oil rated API CK-4 (or CJ-4) with a viscosity of 5W-40. This combination is designed to protect the turbocharged, high-output engine and its emissions system across a wide range of conditions.
For many model years, Mopar and Cummins guidance has centered on using a 5W-40 synthetic diesel oil that meets API CK-4 or CJ-4 specifications. The exact capacity and change intervals can vary by year and driving conditions, so it’s important to consult your owner’s manual or the oil-life monitor in the vehicle for precise guidance. In general, the Ram 3500’s 6.7L uses around 13 quarts of oil with a new filter when performing an oil change.
Recommended oil specifications
When selecting oil for the Ram 3500’s 6.7L Cummins, focus on the following specifications to ensure proper protection and performance.
- Viscosity: 5W-40 (preferred for a wide operating temperature range and engine protection).
- Type: Full-synthetic diesel engine oil.
- API service classifications: CK-4 or CJ-4 (or newer CK-4/FA-4 as approved by your vehicle’s manufacturer).
- OEM approvals: Look for oils that meet Mopar/Cummins recommendations and any applicable OEM certifications.
In choosing oil, prioritize correct viscosity and API classification above brand alone. The right spec helps protect turbochargers, emissions controls, and piston rings under heavy-duty use.
Oil capacity and service intervals
Here are the practical figures most Ram 3500 owners rely on, with the caveat that exact values can vary slightly by year and filter choice.
- Oil capacity: Approximately 13 quarts (about 12.3 liters) with a new filter.
- Change interval: Follow the Oil Life Monitoring System; typical normal-service intervals can reach up to 15,000 miles, while severe-service conditions may require more frequent changes (often around 7,500–10,000 miles, depending on conditions).
- Oil filter: Replace at every oil change to ensure proper filtration and protection.
Always adhere to the vehicle’s oil life monitor and the owner's manual for the exact capacity and interval for your specific year and usage pattern.
Climate and model-year considerations
Model-year updates and climate can influence oil choice and intervals. 5W-40 synthetic diesel oil remains the standard recommendation across most recent Ram 3500 6.7L applications, but some older versions or unusual environments may necessitate adjustments. When in doubt, verify the latest guidance in the owner’s manual or consult a dealer service advisor to confirm the correct specification for your exact truck.
Why the right oil matters
Using the correct oil helps maintain engine longevity, protects against wear in high-load conditions, and supports the efficiency of the emissions system. Diesel engines like the 6.7L Cummins benefit from high-quality, synthetic oil that resists shear and maintains viscosity over time.
Summary
For a Ram 3500 with the 6.7L Cummins diesel, the standard choice is a full-synthetic diesel oil that meets API CK-4 (or CJ-4) with a viscosity of 5W-40. Expect about 13 quarts of capacity with a filter, and follow the vehicle’s Oil Life Monitoring System or the owner’s manual for service intervals. Always verify the exact spec for your model year and driving conditions to ensure optimal protection and performance.
