You are standing in the aisle with a jug of diesel oil in each hand, or you are about to do the first oil change yourself on a truck you just bought, and the question is simple. How much oil does the 6.7 litre Cummins take, and which oil is it supposed to be? The short answer on Cummins oil capacity: the 2022 Ram 2500/3500 owner's manual lists 11.4 litres (12 quarts) with the filter, in 10W-30 above minus 18 Celsius and 5W-40 synthetic below. On a diesel that cost what yours did, a guess is a bad trade. If you would rather skip the reading, book a Cummins oil change with our service team in Portage la Prairie and ask which grade and filter your VIN calls for.

The good news is that the owner's manual answers both questions plainly, and we will walk through exactly what it says. If you drive a half ton, this is the wrong page: our Ram 1500 oil type and capacity guide covers the gas engines.

Key Takeaways

• The 6.7 litre Cummins holds 11.4 litres (12 quarts) with the filter, according to the Fluid Capacities table in the 2022 Ram 2500/3500 owner's manual.
• Above minus 18 Celsius, the manual recommends 10W-30. Below minus 18, it recommends 5W-40 synthetic. Both must meet Chrysler Material Standard MS-10902 and the API CK-4 category.
• In a Manitoba winter, the 5W-40 synthetic question is the whole question. If your truck starts on mornings colder than minus 18, that is the grade the manual points to.
• Change the filter at every oil change. The manual says so in plain words.
• The interval has three limits, not one: kilometres, months and engine hours, or sooner if the oil change indicator asks. Idling counts toward the hours.

How Much Oil Does a 6.7 Cummins Hold?

The Fluid Capacities table in the 2022 Ram 2500/3500 owner's manual, published by Mopar, lists engine oil with filter for the 6.7L diesel at 11.4 litres, or 12 quarts. That is the figure for an oil change that includes a new filter, which is the only kind of oil change the manual describes.

That is a lot more oil than a half ton holds, and it is one reason a Cummins oil change is not a quick in and out at a lube place that mostly sees cars. At 11.4 litres, check the size printed on the jug, and if you are buying for yourself, buy enough.

Check your own year. The figures in this post are from the 2022 Ram 2500/3500 owner's manual, the year we could read directly in Mopar's online manual, and they are not confirmed for other model years or for the high output engine. If your truck is older or newer, or has the high output Cummins, open the Fluid Capacities table in your own owner's manual or ask our team with your VIN before you buy. We would rather you check than trust a number from a forum, and a lot of the numbers floating around online do not cite a manual at all.

Fill, run, then read the dipstick. Add most of the oil, start the engine briefly so the filter fills, shut it off, give it a few minutes to drain back, and check the dipstick on level ground. Top up from there. Overfilling a diesel is not extra protection.

Which Oil the Manual Calls For

This is where the Cummins is different from the gas trucks. The manual gives two recommendations, and the dividing line is the outside temperature.

Above minus 18 Celsius (0 Fahrenheit): the 2022 manual recommends 10W-30 engine oil that meets Chrysler Material Standard MS-10902, and it says the API CK-4 engine oil category is required. It names Mopar, Shell Rotella and Shell Rimula as examples.

Below minus 18 Celsius: the manual recommends 5W-40 synthetic engine oil, meeting the same MS-10902 standard and the same CK-4 category.

Read the whole label, not just the grade. A jug can carry the right viscosity and still be the wrong oil if it does not carry the MS-10902 approval and the CK-4 category. Diesel oil is formulated for soot and for the emissions equipment on a modern Cummins. That equipment is a big reason the right oil matters, and our post on the Cummins DEF system explains the other half of that system.

Other model years. Go by the manual for your model year. If you bought the truck used and the manual is missing, ask our parts department what your VIN calls for.

The Minus 30 Question: 10W-30 or 5W-40 in Manitoba?

Here is the Manitoba angle, and it is the reason this post exists.

The manual's line is minus 18. If your truck sees mornings colder than that, the manual is pointing you to 5W-40 synthetic for that season.

The W number is the cold rating. A 5W oil flows more easily at a cold start than a 10W oil, and the cold start is where a diesel takes its hardest wear. Thick oil takes longer to reach the top of the engine and the turbocharger after you turn the key.

So what do we tell people? Look at when your oil change falls. A truck that gets its fall oil change in October or November is going to live in that oil through the coldest part of the year, and that is the change where the cold weather recommendation matters. If you are not sure which grade is in your engine right now, book your service and ask our service team which grade your VIN calls for.

Oil is only part of a cold start. Plugging in matters just as much, and our block heater guide for Manitoba covers when and for how long.

The Oil Filter

The 2022 owner's manual is short and clear on this: replace the engine oil filter with a new filter at every engine oil change. It calls for a full flow disposable filter and says only high quality Mopar certified filters should be used.

We are not printing a part number here on purpose. Ask our parts department which filter your VIN calls for. The fuel filters are a separate job with their own interval, and our post on the Cummins fuel filter change interval covers them.

How Often to Change It, and How the Oil Change Indicator Works

The diesel maintenance plan in the 2022 manual says to change the engine oil every 24,000 km (15,000 miles), or 12 months, or 500 hours, or sooner if the oil change indicator system prompts you, whichever comes first.

Most people remember the kilometres. The other two limits are the ones that catch Manitoba trucks.

The oil change indicator is duty cycle based. The manual says the interval "may fluctuate, dependent upon your personal driving style." In plain terms, the truck watches how it is actually used, and hard use brings the Oil Change Required message up sooner than the kilometres would suggest.

Idling counts as hours, not kilometres. A Cummins that sits idling at a job site all day through the winter, running the heater for a crew or keeping the cab warm between loads, can pile up engine hours while the odometer barely moves. That truck can show the reminder at what looks like low kilometres. The hours limit is why. Short winter trips that never get the engine fully warm are hard on oil too. If that sounds like your truck, ask our service centre about the hours limit when you book.

Twelve months is a limit even if you barely drove. A Ram 3500 that pulls a fifth wheel in summer and sits in the shed all winter still needs its oil changed once a year.

If idling is part of your routine, our post on whether you should warm up your diesel in the cold is worth a read. When you change the oil yourself, reset the indicator afterward. The 2022 owner's manual lists two methods under Oil Life Reset, one through the Vehicle Info menu and one using the accelerator pedal with the ignition on and the engine not started.

FAQs

What is the Cummins oil capacity in a Ram 2500 or 3500?

The 2022 Ram 2500/3500 owner's manual lists 11.4 litres (12 quarts) with the filter for the 6.7L diesel. Check the Fluid Capacities table in your own manual for your model year, or ask us with your VIN.

What oil does a 6.7 Cummins take?

Per the 2022 manual, 10W-30 above minus 18 Celsius and 5W-40 synthetic below minus 18, both meeting MS-10902 with the API CK-4 category. Other model years are not confirmed here, so check your own manual.

Should I run 5W-40 in a Manitoba winter?

The manual recommends 5W-40 synthetic below minus 18 Celsius. If your truck sees mornings colder than that, the fall oil change is a good time to ask for it.

How often should I change the oil in my Cummins?

The 2022 manual says every 24,000 km, 12 months or 500 hours, or sooner if the oil change indicator prompts it, whichever comes first.

Does idling affect the Cummins oil change interval?

Yes. The indicator is duty cycle based, and the 500 hour limit counts idling time. A truck that idles a lot can come due long before its kilometres say so.

The Bottom Line

The Cummins is not complicated about oil. It takes 11.4 litres (12 quarts) with a new filter per the 2022 manual, it wants a diesel oil carrying MS-10902 and the CK-4 category, and the grade depends on the temperature, with 5W-40 synthetic below minus 18. In Manitoba, that cold line decides what goes in at the fall change. Watch the hours as well as the kilometres, especially on a truck that idles all winter.

If you would rather hand it off, book your Cummins oil change in Portage la Prairie and ask our service team which grade and filter your VIN calls for. And if you are shopping for your next diesel, browse our new Ram 2500 inventory or our new Ram 3500 inventory.

Tyler Dunn, Dunn Ram Trucks, Portage la Prairie