Explainer
Ram 2500 and 3500 Cummins Diesel Maintenance Schedule, by Year
Oil, fuel filter, DEF, coolant and driveline intervals for the 6.7L Cummins in Ram 2500 and 3500 trucks, 2017-2027, with capacities by year.
By the Midwest CDJR editorsUpdated November 8, 20268 min read
For the 2019 through 2027 model years, the 6.7‑liter Cummins in a Ram 2500 or 3500 has an oil change listed every 15,000 miles, or 12 months, or 500 hours, or sooner if the oil-change indicator asks for it. The fuel filters are on the same 15,000‑mile beat. The truck holds 12 quarts of oil with the filter in every year the research data covers it, 2019 included (see the note on that year below). Earlier diesel schedules (2017 and 2018) are shaped differently, and the 2025 model year has a quirk, so this page walks through each change.
Everything below comes from Mopar's published maintenance tables and the owner's-manual fluid pages for Ram 2500 and 3500 diesel trucks. The 2500 and 3500 tables are identical row for row in every diesel year from 2017 to 2027, so "Ram 2500 Cummins" and "Ram 3500 Cummins" mean the same schedule here. If you work around Midwest grain country or haul a camper out of a state park lot, the heavy-towing notes in the second half of this page are the ones to read twice.
Which years have a diesel schedule at all
The research data holds a separate diesel schedule for the 2500 and 3500 starting with the 2017 Ram 2500 and 2017 Ram 3500. The 2015 and 2016 model years list only gasoline schedules (5.7L and 6.4L), although their capacity and fluid pages do describe the Cummins. That means for a 2015 or 2016 truck the fluid specs below apply, but the research data has no mileage table for the diesel.
The 2019 Ram 2500 is a gap of another kind: its maintenance table covers the 6.7L Cummins in full, but its owner's-manual capacity page lists only the 6.4L gasoline engine (7 quarts of oil), with the diesel pointed to a separate supplement, and its fluid page names no diesel oil grade. The 2019 engineering spec sheet does list the Cummins at 12.0 quarts (11.3 L) with filter, so the capacity matches the other years, but the research data has no 2019 diesel oil grade, and the table that follows marks that column as missing.
Oil: grade and capacity by year
The oil spec splits at 0°F ambient in every year. Above that line you run a conventional diesel grade; below it, a synthetic 5W‑40. The grade changed once.
| Model years | Engine oil with filter | Above 0°F (-18°C) | Below 0°F (-18°C) |
|---|---|---|---|
| 2015 to 2018 | 12 qt (11.4 L) | SAE 15W‑40, API CJ-4 | SAE 5W‑40 synthetic, API CJ-4 |
| 2019 | 12.0 qt (11.3 L), spec sheet only | not in the data | not in the data |
| 2020 to 2027 | 12 qt (11.4 L) | SAE 10W‑30, API CK-4 | SAE 5W‑40 synthetic, API CK-4 |
All years list Cummins CES 20081 oils as also acceptable for the warm-weather grade, and the standard code is MS‑10902. If you buy oil for a 2020 or newer truck from a shelf that still stocks the older 15W‑40, check the label for both the viscosity and the CK-4 rating before it goes in. The 2027 page names Mopar, Shell Rotella and Shell Rimula as example products for the 10W‑30 and 5W‑40 grades.
As for how often: the 2020 Ram 2500 and later schedules say the oil change comes at 15,000 miles or 12 months or 500 hours, whichever happens first, repeating through 150,000 miles. The 2017 and 2018 diesel tables contain no oil-change row at all, so the research data cannot tell you the interval for those two years; use the manual for the specific truck. The 2025 Ram 2500 lists a bare "change the oil" line with no mileage attached, and the 2026 table restores the 15,000‑mile wording.
Capacities that matter: coolant and DEF
| Model years | Cooling system | DEF tank (2500 and 3500) |
|---|---|---|
| 2015 to 2018 | 5.7 gal (21.4 L) | 5.5 gal (21 L) |
| 2020 to 2024 | 22 qt (20.8 L); 22.0 qt in 2020 and 2021 | 5.7 gal (21 L) |
| 2025 to 2027 | 22 qt (21 L) | 7.5 gal (28.4 L) |
Two things stand out. First, the coolant figure appears in gallons through 2018 and in quarts afterward, and 5.7 gallons is not 22 quarts, so the pages disagree somewhat; the research data records what each manual printed, and the engineering spec sheets add a third figure for the Cummins: 23.8 quarts (22.50 liters) in every year from 2016 to 2027 (the 2015 sheet gives only the 22.50 L). Second, the DEF tank grew to 7.5 gallons starting with the 2025 model year, a jump of 1.8 gallons over the 5.7‑gallon tank used from 2020 to 2024 (computed from the two table values). The 2015 to 2018 pages also list a 9‑gallon DEF tank for Chassis Cab; from 2020 on, the 2023 Ram Chassis Cab and its neighbors list 8.7 gallons. The fluid standard for DEF is ISO 22241, and the coolant is a 10-year, 150,000‑mile OAT formula in every year.
The 2019 to 2027 schedule in plain words
Think of the diesel plan as four rhythms.
Every 7,500 miles (6 months). Check the DEF tank and top it off. Rotate the tires. Lubricate the front end if it has serviceable fittings. Inspect the CV and universal joints. This is the cheap, frequent visit.
Every 15,000 miles (12 months). Change the oil and filter, replace the fuel filters, inspect the front suspension, tie-rod ends and boot seals, and inspect the engine air filter.
Every 22,500 miles (18 months). Inspect brake linings, adjust the parking brake, inspect the drive belt, inspect the axle surfaces (from 2022; see below), and replace the cabin filter in the 2019 to 2021 trucks.
Longer jumps. Wheel-bearing inspection every 30,000 miles. Transfer case fluid at 60,000 and 120,000 miles, with transmission fluid following the year-by-year table below. The crankcase ventilation (CCV) filter at 75,000 and 150,000 miles. Power steering fluid at 97,500 miles. Engine coolant at 150,000 miles (the 2024 to 2027 tables add 120 months).
How the schedule changed, year to year
| Service | 2017 and 2018 | 2019 to 2024 | 2025 to 2027 |
|---|---|---|---|
| Engine oil | no row | every 15,000 mi | every 15,000 mi in 2026 and 2027; no mileage in 2025 |
| DEF | "completely fill" every 10,000 mi | check and refill every 7,500 mi | check and refill every 7,500 mi |
| Fuel filter | replace every 20,000 mi; drain water from the filter assembly every 10,000 mi | engine filter element and chassis-mounted filter, each every 15,000 mi | front and rear engine fuel filters, each every 15,000 mi |
| Engine air filter | replace every 30,000 mi | inspect every 15,000 mi, replace if necessary | same as 2019 to 2024 |
| CCV filter | no row | 75,000 and 150,000 mi | 75,000 and 150,000 mi |
| Transmission fluid | no diesel row | 2019 to 2024: AS69RC fluid every 30,000 mi up to 120,000; 68RFE fluid and filter at 60,000 and 120,000 for fleet-type or frequent towing use, plus an unconditional fluid-and-filter row at 120,000 | 2025: 60,000 mi only; 2026 and 2027: 60,000 and 120,000 mi |
| Coolant | listed at 100,000 and 150,000 mi, text says 10 years or 150,000 mi | 150,000 mi | 150,000 mi |
The biggest shift happens at the 2019 Ram 2500. The water-drain row disappears, the DEF row becomes a 7,500‑mile check, the air filter changes from a fixed replacement to an inspection, and the oil change enters the table. The 2018 Ram 2500 is a carbon copy of 2017 in the research data. The 2025 trucks list a single transmission fluid change at 60,000 miles, and by 2026 that has returned to 60,000 and 120,000 miles.
The air filter row deserves a note because it applies to dusty work: from 2019 on, the table says the element should never go past 30,000 miles or 24 months, whichever comes first, even if an inspection says it looks fine.
Normal versus severe duty
The Cummins tables do not come in two versions, one normal and one severe. Instead, certain rows carry a conditional note. A condition list covering police, taxi and fleet work, off-road use and frequent towing is attached to the axle fluid in every diesel year (the transfer case note uses the same list minus off-road), and in 2019 through 2024 a shorter list (police, fleet or frequent towing) attaches to the 68RFE automatic transmission's fluid-and-filter change. For those uses, the manual says to change the axle fluid, rather than just inspect it. The tables do not turn these notes into mileage numbers of their own (with one exception: the 2019 through 2021 text says to do the axle inspection every 20,000 miles, while the 2022 and later tables use 22,500 miles).
If you tow a loaded fifth-wheel several hundred miles at a stretch, that note likely describes your truck. The data defines no hours-per-year or trailer-weight threshold for "frequent," so whether you qualify is your call.
Truck by truck: who has what
- 2020 Ram 2500: oil 10W‑30 CK-4 above 0°F, 12 qt, DEF tank 5.7 gal, coolant capacity 22.0 qt, and the 2019-style table with the 7,500‑mile DEF check.
- 2021 Ram 3500: same schedule, with the 6.7L engine codes listed as ETL and ETM.
- 2024 Ram 3500: last 3500 year with a 5.7‑gallon DEF tank, and the last year the 2500 and 3500 tables use the "chassis mounted fuel filter" wording.
- 2027 Ram 2500: 7.5‑gallon DEF tank, front and rear engine fuel filters (3-micron front, 5-micron rear), coolant at 150,000 miles.
For Chassis Cab trucks, the diesel schedule in 2020 through 2027 follows the same oil, DEF and fuel-filter intervals (15,000, 7,500 and 15,000 miles), and the engine codes read ETN. In 2026 and 2027 the data labels the diesel table first and the gasoline one second, the reverse of earlier years, so a quick scan of the heading helps.
How to check your own truck
Run your VIN through the VIN decoder to pin down the model year and engine, then open that year's page, such as the 2022 Ram 2500, to see the table and fluids for your specific truck. The spec explorer lets you jump between years, and the towing hub covers the trailer side if you tow often. Model hubs for the Ram 2500 and Ram 3500 list every year at once.
