When towing or hauling with a 2018 Ram 2500, knowing the 6.4L HEMI V8 oil capacity helps you maintain peak performance and longevity. Using the correct amount of oil reduces engine wear and keeps your heavy-duty drivetrain running smoothly under load.
This guide breaks down key specifications, maintenance procedures, and best practices specific to the 6.4L V8 in the 2018 Ram 2500. Use the details below to plan an accurate oil change and avoid common mistakes.
| Engine | Oil Capacity | Filter Type | Recommended Oil |
|---|---|---|---|
| 6.4L HEMI V8 (2018 Ram 2500) | 7.5 quarts (with filter) | Standard cartridge | SAE 15W-40 synthetic blend or conventional diesel oil |
| Diesel applications | Approximately 7.5 quarts | Heavy-duty cartridge | CI-4 or CK-4 rated 15W-40 |
| Gasoline options | Approximately 6.6 quarts | Standard cartridge | SP or SN plus 5W-30/10W-60 depending on climate |
| Includes filter | Yes, system accounts for filter | Micron filtration | Match OEM drain plug torque specs |
6.4L HEMI V8 Oil Capacity and Specifications
The 6.4L HEMI V8 in the 2018 Ram 2500 has specific oil capacity requirements depending on whether it is paired with a diesel or gasoline tune. Knowing the exact volume ensures you do not underfill or overfill during service.
For diesel models, the sump holds roughly 7.5 quarts when including the replacement filter. Always confirm the filter type and micron rating to match OEM performance and contamination control expectations.
When using conventional gasoline tune setups, the capacity settles closer to 6.6 quarts. Choosing the correct SAE grade and meeting API rating targets further protects the V8 under varying duty cycles and climate conditions.
Factory Fill vs Aftermarket Filter Impact
Factory fill procedures account for the stock filter size and internal engine passages, which directly influence total oil capacity. Aftermarket filters with different media or bypass settings can alter effective capacity slightly.
Technicians should check oil level after fitting any replacement filter, especially when using high-flow or racing-style cartridges. Small changes in filter design affect the amount needed to achieve proper lubrication pressure and oil life.
If you alternate between OE and aftermarket filters, follow the procedure below to verify exact capacity without relying solely on generic specifications:
Verification Procedure
Drain old oil completely, install the new filter, add manufacturer-recommended oil until dipstick reads full, then run the engine briefly and recheck level once settled.
Diesel vs Gasoline Oil Formulation Differences
Diesel engines in the 2018 Ram 2500 generate higher combustion pressures and soot loads, requiring oil formulations with enhanced detergency and soot tolerance. These formulations often meet CI-4 or CK-4 standards and support longer drain intervals under severe use.
Gasoline variants emphasize fuel economy and cold-start protection, with lower viscosity grades such as 5W-30 or 10W-60 depending on climate. Selecting an oil that matches both the engine type and driving conditions is essential for balancing protection and efficiency.
Key formulation highlights include:
- Diesel: Higher total base number, improved soot handling, and robust anti-wear additives
- Gasoline: Balanced friction modifiers for efficiency and compatibility with emission controls
- Synthetic options: Improved temperature stability and consistent viscosity across operating range
- Filter pairing: Use a filter rated for the chosen oil formulation to maximize service life
Best Practices for Oil Changes
Performing oil changes at the recommended intervals and capacities keeps the 6.4L HEMI V8 in top condition for towing, hauling, and daily driving. Consistent service intervals also preserve warranty coverage and resale value.
Use a calibrated drain pan and appropriate lifting equipment to ensure complete evacuation and safe access. Measuring tools and fresh crush washers prevent leaks and incorrect torques on the drain plug and filter.
Follow this checklist for a thorough service:
- Warm up engine briefly to suspend contaminants, then shut off and drain fully
- Replace factory filter with a compatible aftermarket or OE replacement
- Add oil gradually, checking level frequently to approach full mark
- Torque drain plug and filter to factory specifications with new gaskets
- Run engine, cycle accessories, recheck level, and inspect for leaks
Maintenance Recommendations for Long-Term Reliability
Staying consistent with oil capacity and service intervals directly affects durability, fuel economy, and towing confidence for your 2018 Ram 2500. Using quality filters and correct formulations protects critical components under heavy loads.
- Stick to factory capacity and do not guess volumes from generic charts
- Choose oil ratings that align with your climate and usage severity
- Replace filters with compatible, high-efficiency cartridges
- Check oil level after short drives and before long trips
- Keep records of change dates, capacities, and filter types
FAQ
Reader questions
How much oil does a 2018 Ram 2500 6.4 diesel engine require with a new filter?
Expect approximately 7.5 quarts of oil when including the replacement filter for a 6.4L diesel in the 2018 Ram 2500. Always verify by measuring after installation.
Can I use 5W-40 in my 6.4L Hemi Ram 2500 for better protection?
Yes, 5W-40 synthetic diesel oil is suitable if it meets CI-4 or CK-4 specifications and matches the recommended capacity. Confirm compatibility with your climate and towing demands.
Does the gasoline 6.4 engine hold the same amount of oil as the diesel version?
No, the gasoline 6.4L HEMI typically requires around 6.6 quarts, since the block and filter packaging differ from the diesel layout.
What happens if I overfill the oil in my 2018 Ram 2500 6.4 engine?
Overfilling can increase oil pressure, cause leaks, foam, and reduce lubrication efficiency. If you suspect an overfill, drain or extract oil to reach the proper level.