What Is The Best Oil For A Ram 2500 Diesel?

With so many oil grades and brand options available, selecting the right one for your vehicle might be a bit overwhelming. Should you be driving a Dodge Ram 2500 diesel and are wondering what oil is best for its engine, we can help you. We researched this popular pickup truck from multiple professional sources so that you'll know which one to use.

The best oil for a Dodge Ram 2500 diesel is Mopar 10W-30 or Mopar 5W-40, depending on the outside temperatures you will be driving the vehicle in.

Now that we know that the best oil for the Dodge Ram 2500 diesel will be Mopar 10W-30 or Mopar 5W-40, we'll look at when you should use which one.

You might also be curious how often you should change the oil in your Ram 2500 or how much oil a 6.7 Cummins engine takes. For the answers to these questions and more, read ahead in this post and see what we've discovered with our research.

Ram 2500 Heavy Duty parked on the street. This vehicle is one of the most popular pick-up trucks in North America - What Is The Best Oil For A Ram 2500 Diesel

How outside temperatures affect what oil you use in your Ram 2500 diesel

Earlier in this post, we mentioned two different types of oil that the owner's manual recommends for the Ram 2500 diesel. Powered by a 6.7L Cummins engine under its hood, the Ram 2500 is a formidable machine. But even the strongest engines need proper care and maintenance, nothing being as important as the correct motor oil.

When to use 10W-30 oil for the Dodge Ram 2500 diesel

In most cases, using Mopar 10W-30 oil will work perfectly for this model pickup truck. Its viscosity works when the temperatures outside are hot and continue to operate whenever the weather turns cold.

In certain areas, you'll find that this oil is not the best, however. If you drive this vehicle in a place that is routinely cold, you'll want to consider the other oil we mentioned.

When to use 5W-40 oil for the Dodge Ram 2500 diesel

Auto Mechanic Showing 5W-40 Engine Oil in the Auto Repair Shop

The Mopar 5W-40 oil works better than its counterpart for operating the engine in extremely cold temperatures. If the thermostat outside reads below 0 degrees Fahrenheit, you'll want to use an oil that doesn't have as much viscosity. Oil will freeze at temperatures much lower than water. But that doesn't mean the cold won't slow down its flow.

Using this grade of engine oil means that the oil coursing through the engine will be thinner. Thinner oil means it won't need to sit in an idling engine forever before it comes to temperature and can flow through it. 

How often should I change the oil in my Ram 2500 diesel?

You'll get the most life and the best performance out of your Ram truck if you maintain it properly. A big part of the routine maintenance schedule is making sure that you have the oil and oil filter changed at the proper intervals. You'll find that doing this with a diesel engine is quite a bit different than with an engine that runs off of standard gasoline.

Those who drive a gasoline-powered vehicle will need to change the oil every 3,000 miles (conventional motor oil) or every 7,500 to 10,000 miles [synthetic motor oil].

You'll be able to drive a diesel engine a lot further than this between changes. The Ram 2500 owner's manual recommends changing the oil from its 6.7L Cummins engine every 15,000 miles. 

You will need to change the oil in this engine sooner if you exceed 12 months since the last change or have 500 hours of drive time. Just as important, pay attention to the oil change indicator system. If it alerts you to change the oil before any of the above has occurred, schedule an oil change as soon as possible.

Fill in high-quality engine oil

How many quarts of oil does a 6.7L Cummins engine take?

The big machine under the hood of the Dodge Ram 2500 will take more oil than you might have thought initially. All the moving parts of this engine need a good amount of oil to keep them lubricated and cooled.

For the Cummins engine to operate properly, it will require 12 quarts of approved motor oil. 

How often should I change the fuel filter on a 6.7L Cummins engine?

The fuel filter helps to keep contaminants from the gas tank from invading your engine. These can enter by using fuel that has been polluted or from the natural breakdown of the interior of the tank over time. But no matter how these contaminants get into your fuel line, you'll want to be sure that they are filtered out.

If you drive a Ram 2500 diesel, you'll need to change the fuel filter every 24,000 miles. A new filter will ensure that unwanted debris from the fuel tank is kept from harming the moving parts of the machine that powers your pickup truck.

Car mechanic replace the new fuel filter at modern diesel engine. car service or preventive maintenance.

Why you should change your oil regularly

The motor oil that surges throughout your vehicle's engine serves as the lifeblood of the machine that propels it. No matter how tough of an engine, it requires this substance to keep operating smoothly and effectively. 

Just putting oil into the crankcase is not enough. You'll need to change the oil out at the recommended intervals, so the engine continues doing its job.

Over time, the oil will pick up contaminants, become thicker and sludgy, and will not be able to flow through the engine as manufactured.

Regular oil changes should be done for several reasons. Let's take a look at why they are so important.

The oil won't be able to lubricate properly.

The primary function of motor oil is to lubricate. The engine under your vehicle's hood contains many moving parts, each of which needs oil to act as a lubricant.

If the oil isn't present, these parts grind together and suffer significant damage. If the oil is past its useful life, it won't lubricate these parts as effectively, also damaging them.

Oil will become thicker as it picks up contaminants from the engine. After all, engines are hot and dirty places, so it's natural for the oil to pick up some of the carbon deposits and other internal debris as it flows through and does its job.

Changing the oil regularly will ensure that it will flow through the engine at the correct rate. New oil is also better at absorbing the various buildups that might otherwise impede the moving parts contained therein. 

Old oil doesn't cool the engine as effectively.

Motor oil, car engine close up

Engine oil doesn't just lubricate. It also acts as an effective coolant. The oil moves through the engine and carries away some of the heat that the moving parts generate. 

If the oil is old, it won't be able to act as a coolant as well. This can cause the engine to overheat.

Change your oil regularly to ensure that the engine stays cool while working hard.

The fuel economy will suffer if you don't change the oil.

The harder an engine has to work, the more fuel it will need to consume. Old oil will not flow correctly through the engine, making the moving parts work even harder.

If you go too long between oil changes, you might notice that you aren't getting as many miles on a full tank as you were accustomed to. The fuel economy won't be the only thing that will suffer, however.

The life of the engine will be greatly reduced if the oil is not changed

Not changing the oil regularly will cause a lot of premature wear on the engine's moving parts. The excess heat, the additional friction, and the buildup of deposits greatly impact the useful life of the engine.

Consult your owner's manual, so you know when to have this vital fluid changed. Like with any component of the maintenance schedule, follow it, and you'll get the most life out of your vehicle.

Young Hispanic mechanic draining engine oil from a car for an oil change at an auto shop

Final thoughts

The oil you should use for the Ram 2500 diesel will depend on the temperatures you subject the vehicle to, but Mopar 10W-30 will work the best under most conditions.

Change the oil at the recommended intervals to get better performance and more life out of your truck. Additionally, be sure to change the fuel filter and follow all the factory-recommended maintenance schedules so that Ram 2500 will be on the road for years to come. Drive safe!

We hope this post on the Dodge Ram 2500 answers all of your questions. For additional information, we recommend reading the following posts:

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Ram 2500 Tradesman Vs. Big Horn Vs. Laramie —Which Is Right For You?

Dodge Ram Key Fob Not Working – What's Wrong?

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