2018 Ram 3500 Oil Capacity & Filter Guide

The 2018 Ram 3500 takes 12.0 quarts (11.4 liters) of oil for the 6.7L Cummins Turbo Diesel engine or 7.0 quarts (6.6 liters) for the 6.4L HEMI V8 engine. Whether you use your heavy-duty Ram for towing fifth-wheel trailers across the country or hauling equipment to the job site, maintaining proper engine lubrication is the single most important maintenance task you can perform.

As an ASE-certified master technician, I've serviced countless Ram heavy-duty trucks. Below is everything you need to know about the oil capacity, recommended viscosities, filter part numbers, and drain plug torques for the 2018 Ram 3500.

Quick Answer: 6.7L Cummins (Most Popular)

Because the overwhelming majority of 2018 Ram 3500s are equipped with the legendary Cummins diesel, here are the quick specs for that specific powertrain:

• Oil Capacity: 12.0 quarts (11.4 L) with filter change
• Recommended Weight: 15W-40 (for temperatures above 0°F) or 5W-40 Synthetic (for temperatures below 0°F)
• Oil Specification: API CK-4 / Cummins CES 20081
• OEM Oil Filter: Mopar MO-285 or Fleetguard LF16035
• Aftermarket Filters: Fram PH3976A, Wix 57620, Mobil 1 M1-403

Note: If you have the 6.4L gas engine, see the table below for your specific requirements.

Capacity by Engine Option

The 2018 Ram 3500 was offered with two main engine choices. Here is the breakdown for both powertrains:

Engine	Oil Capacity (with filter)	Recommended Viscosity	Oil Spec / Filter OEM
6.7L Cummins Turbo Diesel (Standard & High Output)	12.0 Quarts (11.4 L)	15W-40 or 5W-40 (Synthetic)	API CK-4 / Mopar MO-285
6.4L HEMI V8 (Gas)	7.0 Quarts (6.6 L)	0W-40 Synthetic	MS-12633 / Mopar MO-339

Aftermarket filters for the 6.4L HEMI V8 include Fram PH10060 and Wix 57060.

Oil Change Interval

Following the correct interval is vital, particularly for the 6.7L Cummins which works incredibly hard under load.

6.7L Cummins Turbo Diesel:

• Normal / Severe Duty: Ram recommends changing the oil and filter at 15,000 miles, 6 months, or 500 engine hours, whichever comes first. Even under severe duty (heavy towing, excessive idling), you should not exceed these limits. If the EVIC (Electronic Vehicle Information Center) alerts you to change the oil sooner, follow the system's prompt.

6.4L HEMI V8:

• Normal Duty: Follow the automatic Oil Life Indicator (up to 8,000 miles or 12 months).
• Severe Duty: Change every 4,000 to 5,000 miles if frequently towing, off-roading, or idling for extended periods.

Drain Plug Torque

Getting the drain plug tightness right prevents stripped oil pans and annoying driveway leaks.

• 6.7L Cummins: 37 ft-lbs (50 Nm)
• 6.4L HEMI V8: 25 ft-lbs (34 Nm)

Always inspect the drain plug threads and the built-in sealing flange or gasket. If the gasket is compressed, torn, or damaged, replace the drain plug or the crush washer (if applicable) before refilling.

How to Change the Oil

Changing the oil on a 2018 Ram 3500 is very straightforward thanks to the truck's high ground clearance.

1. Prepare the Vehicle: Park on a level surface, set the parking brake, and allow the engine to cool slightly so the oil is warm but not scalding.
2. Drain the Oil: Position a high-capacity drain pan (must hold at least 4 gallons for the Cummins) under the oil pan. Remove the drain plug and let the oil drain completely.
3. Replace the Filter: For the Cummins, access the filter from underneath the passenger side. Use a filter wrench to loosen it. Tip: The Cummins filter holds a lot of oil and is mounted straight up. Use a plastic grocery bag around the filter as you unscrew it to catch the spill. Lubricate the new filter gasket with clean oil, pre-fill it slightly if desired, and spin it on hand-tight plus a quarter turn.
4. Reinstall Drain Plug: Thread the drain plug in by hand to avoid cross-threading, then torque it to spec (37 ft-lbs for diesel, 25 ft-lbs for gas).
5. Refill: Add the correct amount of oil (12 quarts for diesel, 7 quarts for gas).
6. Verify & Reset: Start the engine, check underneath for leaks, shut it off, and verify the oil level on the dipstick. Finally, reset your dashboard oil life monitor.

Common Issues & Tips

• The Cummins Filter Mess: The location of the 6.7L oil filter practically guarantees oil will spill onto the front axle/steering components. Besides the plastic bag trick, you can buy specific threaded filter plugs from aftermarket diesel suppliers that cap the filter before you drop it down.
• Fuel Dilution: If you notice the oil level in your 6.7L Cummins is actually rising on the dipstick over time, this can indicate fuel dilution caused by frequent DPF regeneration cycles. Don't ignore this; excessive fuel in the oil degrades viscosity and can wipe out engine bearings.
• Choosing Diesel Viscosity: If you live in a climate that frequently drops below freezing (0°F), strongly consider running a full-synthetic 5W-40 CK-4 oil year-round. It flows much better during cold starts, protecting your expensive turbocharger bearings.

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