The Ram 2500 with the 6.7-liter Cummins diesel uses a 5W-40 full-synthetic diesel engine oil that meets API CK-4 (CJ-4 is acceptable for older engines). The engine holds about 12 quarts of oil with a filter. Always verify the exact specification for your model year in the owner's manual or with a dealer.
Oil specifications for the Ram 2500 6.7L Cummins
These are the core requirements to guide your choice of oil and maintain optimal engine health.
- Viscosity: 5W-40 synthetic diesel engine oil
- API service category: CK-4 (CJ-4 is acceptable for older engines or if specified by your manual)
- Oil type: Full synthetic recommended for best protection and emissions compatibility
- Oil capacity: Approximately 12 quarts (11.4 L) with an accompanying oil filter
- OEM guidance: Mopar 5W-40 Diesel Engine Oil is commonly recommended, but any brand meeting CK-4/CJ-4 specs is acceptable
In practice, using a high-quality synthetic diesel oil that meets CK-4 (or CJ-4) specifications ensures proper protection for the turbocharged, emissions-equipped Cummins engine across varying climates and towing demands.
Choosing oil by climate and usage
The standard recommendation is 5W-40 synthetic diesel oil for most conditions. This viscosity provides reliable cold-start protection and strong high-temperature stability needed for heavy-duty work, towing, and frequent fuel shutoffs. If you live in an area with extreme temperatures or have specialized duty cycles, consult your manual or a Ram technician for any climate-specific notes, but 5W-40 CK-4/J-CJ-4 remains the baseline.
Oil change intervals and practical tips
With the 6.7L Cummins and 5W-40 synthetic CK-4 oil, Ram typically targets longer change intervals under normal use—often around 15,000 miles (24,000 km) when using synthetic oil and performing regular maintenance. Severe service, frequent towing, or very hot conditions may necessitate shorter intervals. Always follow the Oil Life Monitoring System (if equipped) and the owner’s manual for exact guidance, and don’t skip filter changes, as a fresh oil filter is essential for optimal flow and protection.
Additional considerations and tips
Use a quality oil filter designed for diesel engines with aftertreatment systems. If you prefer OEM parts, Mopar-branded diesel oils and filters are widely used in the Ram community. Always confirm the exact specification for your model year, as recommendations can shift with new emissions standards and engine revisions.
Summary
For a Ram 2500 with the 6.7L Cummins diesel, the go-to oil is a 5W-40 full-synthetic diesel oil meeting API CK-4 (CJ-4 acceptable). Expect to use about 12 quarts with filter, and follow your manual or dealer guidance for exact interval timing, which is typically around 15,000 miles under normal conditions but may be shorter under heavy towing or extreme environments. Prioritize a reputable CK-4/CJ-4-rated oil to protect the engine and its emissions system.
What oil does a 6.7 Cummins take in a Ram 2500?
15 Liters of Semi Synthetic Eurol Geo Max 15W40 Diesel Truck Oil - Meets or exceeds the recommended Cummins CES 20081, API CK-4, and API CJ-4 oil quality specifications required for the 6.7L Cummins diesel engine.
Can I run 15W-40 in a 6.7 Cummins?
Final Thoughts: Ensuring Your 6.7 Cummins Runs Strong
Whether you're using 15W-40 for older models or 10W-30 for newer ones, selecting the proper oil type ensures optimal engine performance, especially during extreme temperatures or heavy usage. It's just as important to keep a close eye on oil levels.
What is the best oil for a 6.7 diesel engine?
Top Recommended Oils for 6.7 Cummins Engines
- AMSOIL OE Synthetic Motor Oil 5W-40.
- Shell Rotella T6 5W-40 Full Synthetic.
- Valvoline Premium Blue Extreme 5W-40.
- Mobil 1 Turbo Diesel Truck 5W-40.
What's the best Cummins engine ever made?
The 3 Best Cummins Engines
- The Most Reliable Classic: 5.9L 12-Valve (1989–1998) Mechanical simplicity, longevity and ease of maintenance made the early 12-valve legendary.
- The Tuner's Dream: 5.9L Common Rail (2003–2007)
- The Modern Powerhouse: 6.7L (2019–Present)