The 2018 Ram 6.7 oil capacity and type are critical specifications for any owner looking to maintain the legendary Cummins turbo-diesel engine’s performance and longevity. These heavy-duty trucks, renowned for their power, durability, and towing capabilities, rely on precise lubrication to operate efficiently and withstand the rigors of demanding work. Understanding these details isn’t just about routine maintenance; it’s about protecting a significant investment and ensuring your truck serves you reliably for hundreds of thousands of miles. Proper oil selection and maintaining the correct fluid level are paramount to the health of your engine, impacting everything from fuel economy to the lifespan of complex emission control systems.
Understanding the 2018 Ram 6.7L Cummins Oil Capacity
For the 2018 Ram 2500 and 3500 equipped with the 6.7-liter Cummins turbo-diesel engine, the oil capacity is a generous 12 U.S. quarts (11.36 liters) with a filter change. This substantial volume is necessary to adequately lubricate the large components of a diesel engine, dissipate heat effectively, and provide a buffer for extended service intervals. Diesel engines, by nature, operate under higher pressures and temperatures than gasoline engines, leading to greater stress on the lubricating oil. A larger oil sump helps maintain oil quality and temperature stability over time.
It’s crucial to always check your oil level on a flat surface after the engine has been turned off for at least 15-20 minutes. This allows all the oil to drain back into the pan, providing an accurate reading on the dipstick. Overfilling can be just as detrimental as underfilling, potentially causing aeration of the oil, increased crankcase pressure, and seal damage. While the 12-quart capacity is standard, it’s always a good practice to add about 11 quarts initially, run the engine briefly, then shut it off, wait, and top up as needed to reach the full mark on the dipstick.
Choosing the Right Oil Type for Your 2018 Ram 6.7L Cummins
Selecting the correct oil type for your 2018 Ram 6.7L Cummins engine is non-negotiable for optimal performance and compliance with warranty requirements. The manufacturer’s recommendation is the definitive guide. For the 6.7L Cummins, the primary recommendation typically involves a specific viscosity grade and API (American Petroleum Institute) service classification.
Recommended Viscosity:
The most commonly recommended viscosity for the 2018 Ram 6.7L Cummins is SAE 15W-40. This multi-viscosity oil provides excellent protection across a wide range of operating temperatures, which is ideal for the demanding nature of a diesel engine. In colder climates where temperatures frequently drop below freezing, SAE 5W-40 synthetic oil is often recommended or permitted. The lower “W” number indicates better flow characteristics at cold temperatures, allowing for quicker lubrication during cold starts, which is when the most engine wear typically occurs. Always consult your owner’s manual to confirm the best viscosity for your specific climate and operating conditions.
API Service Classification:
Beyond viscosity, the API service classification is paramount. For the 2018 6.7L Cummins, the oil must meet specific diesel engine oil standards. Historically, this has been CJ-4, but with advancements in emission controls and engine technology, the industry standard has shifted to CK-4.
API CK-4 oils are specifically formulated to provide enhanced protection against oxidation, shear stability, and aeration, while being fully compatible with diesel engines equipped with exhaust aftertreatment systems like Diesel Particulate Filters (DPFs) and Selective Catalytic Reduction (SCR) systems. Using an older API classification (like CI-4 or earlier) can lead to premature clogging of your DPF, costly repairs, and potential voiding of your warranty. Always ensure the oil you choose carries the API CK-4 rating on its label.
Synthetic vs. Conventional vs. Blends:
While the owner’s manual specifies the required API classification and viscosity, it often provides flexibility regarding synthetic or conventional oil.
Conventional (mineral) 15W-40 oils meeting CK-4 specifications are perfectly adequate and widely used.
Synthetic 5W-40 CK-4 oils offer superior performance, especially in extreme temperatures (very cold or very hot), providing better flow at start-up and enhanced protection under heavy loads. They can also contribute to slightly extended oil change intervals, though always adhere to the manufacturer’s recommended intervals.
Synthetic blends offer a middle-ground, combining the benefits of synthetics with a more budget-friendly price point.
Regardless of your choice, ensure the oil explicitly states it meets or exceeds the API CK-4 standard and has the correct viscosity for your driving conditions.
Oil Change Intervals and Maintenance Best Practices
For the 2018 Ram 6.7L Cummins, recommended oil change intervals can vary based on driving conditions, but a general guideline is typically 15,000 miles or 12 months, whichever comes first. However, severe duty cycles such as heavy towing, sustained idling, extremely dusty conditions, or frequent short trips may necessitate more frequent changes, sometimes as often as 7,500 miles. Your truck’s onboard maintenance system might also provide notifications based on actual engine usage and oil life monitoring. Always refer to your owner’s manual for the precise maintenance schedule relevant to your vehicle and usage.
Beyond the oil itself, don’t overlook the oil filter. Always use a high-quality oil filter designed for your 6.7L Cummins. Mopar genuine filters are engineered to meet factory specifications, but reputable aftermarket brands also offer excellent alternatives. A quality filter is essential to remove contaminants and maintain oil cleanliness throughout the service interval.
Conclusion
Maintaining your 2018 Ram 6.7L Cummins with the correct oil capacity and type is fundamental to its longevity and performance. Adhering to the manufacturer’s recommendations for 12 quarts of API CK-4 rated oil, with the appropriate viscosity (typically 15W-40 or 5W-40 for colder climates), will ensure your powerful diesel engine receives the lubrication it needs to handle any task you throw at it. Regular oil changes with quality components are a small investment that pays huge dividends in reliability and avoiding costly repairs down the road.
Source:
Always consult your specific 2018 Ram 2500/3500 Owner’s Manual and/or the official Ram service documentation for the most accurate and up-to-date information regarding oil capacity, type, and maintenance schedules.