The 2018 Ram 2500 diesel appeals to buyers who want serious towing capacity paired with proven efficiency. Understanding the oil capacity and related maintenance details helps owners protect their investment and keep the powertrain running smoothly.
This guide covers the specific oil capacity, filter locations, maintenance intervals, and practical tips for both DIYers and those using service centers.
| Specification | Value | Notes |
|---|---|---|
| Engine | 6.7L Cummins I6 Turbo Diesel | Factory installed for 2018 |
| Drain Plug Capacity | Approximately 19–20 quarts (18–19 liters) | Typical figure with standard filter |
| Filter Element Capacity | Approximately 1–2 quarts (1–2 liters) | Helps reach full system capacity |
| Total Filled Capacity | Approximately 21–22 quarts (19.5–20.5 liters) | Factory fill including filter |
| Recommended Oil Type | CJ-4 or CK-4, 15W-40 synthetic or blend | Check Ford specification on oil cap or manual |
Understanding the 6.7L Cummins Oil System
The 6.7L Cummins in the 2018 Ram 2500 is designed for durability rather than high rpm performance. Modern oil formulations with CJ-4 or CK-4 rating support longer drain intervals while protecting components in heavy-duty cycles.
This engine includes a large capacity sump and a robust filtration system. During an oil change, the majority of used oil drains from the oil pan plug, but additional oil remains in the filter and galleries, which is why the total system capacity is higher than the pan drain volume alone.
Ford specifies the total oil system capacity to ensure proper lubrication throughout the engine life. Respecting the full capacity and correct oil specification helps maintain warranty compliance and long term reliability.
How to Check and Add Oil Like a Pro
Proper checking procedure gives the most accurate reading on oil level. With the engine off and on level ground, locate the dipstick, pull it clean, wipe it, reinsert fully, and pull it again to check the actual level.
When adding oil between changes or during top ups, pour slowly and pause to check the dipstick. Overfilling can cause increased crankcase pressure, so aim to stay within the upper range on the dipstick without going past the max mark.
Use only oil meeting Ford specifications and with the correct viscosity. Replace the drain plug and crush washer with every oil change, and torque to the factory specification to avoid leaks or stripping.
Oil Filter Location and Replacement Tips
The oil filter on the 2018 Ram 2500 is mounted near the front of the engine, accessible from under the vehicle. Keeping a quality filter on hand ensures a quick swap and minimizes the amount of old oil trapped in the filtration system.
Before installing the new filter, apply a light coat of fresh oil to the gasket. Screw the filter by hand until the gasket seats, then tighten it snug plus a fraction of a turn as recommended on the filter housing.
After installation, run the engine briefly and check underneath for any leaks. Proper filter installation helps prevent premature contamination of the new oil and supports smooth oil flow at cold start.
Maintenance Intervals and Best Practices
Factory maintenance schedules for the 2018 Ram 2500 diesel often recommend oil changes every 10,000 to 15,000 miles, depending on driving conditions and oil type. Severe use, such as towing in hot climates or short trip patterns, may require more frequent service.
Always reset the oil life monitor after a change so the system can provide accurate future reminders. Pairing oil changes with filter replacements maximizes debris capture and keeps oil passages clear.
Periodic checks of the oil level, especially before long towing trips, help identify consumption early. Addressing small issues like minor external leaks promptly prevents larger engine damage down the road.
Key Takeaways for Long Term Reliability
- Know the total oil system capacity, roughly 21–22 quarts for the 6.7L Cummins in the 2018 Ram 2500.
- Always use the correct oil specification, such as CJ-4 or CK-4 15W-40, as called out by Ford.
- Replace the oil filter with every change and install the gasket with fresh oil to prevent leaks.
- Follow a schedule aligned with your driving conditions, and reset the oil life monitor after each service.
- Check oil level regularly, especially before long trips, to catch consumption or external leaks early.
FAQ
Reader questions
How much oil does a 2018 Ram 2500 diesel hold with a new filter?
The total system capacity is approximately 21–22 quarts, including the oil filter, with the 6.7L Cummins using about 19–20 quarts in the pan plus 1–2 quarts for the filter.
What type of oil should I use in my 2018 Ram 2500 diesel?
Use a CJ-4 or CK-4 rated 15W-40 oil, either synthetic or a synthetic blend, that meets Ford specifications for the 6.7L Cummins engine.
How do I check my oil level properly after a fill up?
With the engine off and on level ground, operate the dipstick correctly by cleaning it, reinserting fully, and reading the level to stay within the upper and lower marks.
How often should I change the oil in my 2018 Ram 2500 diesel when towing?
Under regular towing conditions, aim for changes every 10,000 miles or as specified in your owner manual, using severe service replacement intervals to protect the engine and turbocharger.