Many popular and flagship diesel vehicles are equipped with a Cummins engine. If your car is made after 2010, you need quality diesel exhaust fluid (DEF) for it. Here we’ll talk about the best DEF fluid for Cummins.
In this article, you’ll find all the important information you need to know before choosing a DEF product. While there isn’t that much variety, unlike motor oil or gasoline, you still should pay attention and understand why DEF is needed in the first place.
You’ll find out the best DEF options for your vehicle, as well as get answers to questions like how to choose one, how much to get, and what to expect.
Click here to skip to our recommended pick!
- Pure urea
- Low emissions
- Ergonomic handle
- Value for money: 🔥🔥🔥🔥🔥
- Pure urea
- Very popular
- Clear
- Value for money: 🔥🔥🔥🔥
- Best DEF Fluid for Cummins 2019
- Specialized nozzle
- AUS-32
- Value for money: 🔥🔥🔥🔥
- Factory fluid of many cars
- Pure urea
- User-friendly bottle
- Value for money: 🔥🔥🔥🔥
- Pure urea
- Meets specifications
- Available in drums too
- Value for money: 🔥🔥🔥🔥
Overall #1 Rated Pick
Valvoline Premium Blue Diesel Exhaust Fluid
The Valvoline Premium Blue Diesel Exhaust Fluid is our top pick for Cummin engines. This is especially great for vehicles that do a lot of highway driving. With DEF being pricey, you want a lower consumption rate, which this premium-quality product can offer.
More importantly, it can help bring NOx levels nearly to zero, which is good for your vehicle and the environment. It’s compatible with most Selective Catalytic Reduction (SRC) system engines, so you don’t have to worry about compatibility even if your vehicle came with AdBlue from the factory.
As is the case with most Valvoline products, this DEF is made in America. That means that it goes through high-quality checks. Also, they use dedicated equipment for manufacturing this to avoid contaminants.
This is American Petroleum Institue (API) and AdBlue certified and meets the ISO 22241 requirements.
Specifications
- Brand: Valvoline
- Percentage of Urea: 32.5
- Quality: 2.5 gallon
- Part Number: 729566
Pros
- High-quality
- Meets all requirements and standards
- Easy to add
- Contaminant-free
Con
- Expensive
DEF Fluid for Cummins – Buyer’s Guide
Here are all your questions answered before you buy DEF additive for diesel engines:
What is Diesel Exhaust Fluid?
Diesel exhaust fluid or DEF is a solution of deionized water and urea. The composition is 32.5 percent urea, and the rest is water. Think of it as a fuel for your car, which doesn’t help run it but helps bring emissions down.
When it reacts with NOx emitted by the engine in the SCR, it converts it into vapor and nitrogen, which are already abundantly present in the atmosphere. This helps bring the NOx emissions down, which diesel vehicles have been notorious for a long time.
There’s a dedicated tank for DEF in diesel vehicles.
What Year Did DEF Start?
Adding DEF in diesel engines isn’t really a choice as it has been made mandatory. It was introduced in 2010. The EPA’s guidelines asked manufacturers to make diesel vehicles that meet set emission standards, and DEF helps a lot with that.
So if you have a diesel vehicle model 2010 or above, your car would also need DEF.
How Long Does DEF Fluid Last?
The shelf life of DEF fluids is typically two to three years. As for the consumption, it depends on the DEF itself and your driving and vehicle performance.
DEF is used in conjunction with the fuel, as it’s kind of like fuel for your truck or car. For measuring consumption, the standard in the industry is the percentage of fuel usage. Normally, this varies between 2 and 5 percent of the amount of fuel you use in day, week, or year.
As an example, if you use 1000 gallons a year, you’ll need 30 gallons of DEF if the consumption rate is 3 percent. Given that most tanks take 5 gallons, you’ll have to refill the tank at least six times a year.
Can DEF Freeze?
Of course, since DEF is a liquid, it has the potential to freeze in sub-zero temperatures. Normally, the DEF freezing point is -11 degrees Celcius or 12 degrees Fahrenheit.
This is why diesel vehicles are equipped with a DEF heater that keeps it warm in winters.
RAM 2500 DEF Capacity
Since RAM 2500 is one of the most popular trucks with a Cummins engine, let’s take that for consideration exactly how much DEF its tank can hold at a time.
Again, it varies for vehicles, so you’ll need to search for your specific make and model with Cummins.
Here’s how much DEF capacity is for RAM 2500 over the years:
| DEF | Gallons |
| 2018 RAM 2500 DEF Tank Capacity | 5 gallons |
| 2016 RAM 2500 DEF Tank Capacity | 5 gallons |
DEF Price
DEF isn’t cheap, but you can find cheap products. Rates vary a lot, even for the same product depending on where you’re buying from.
When choosing based on cost, don’t just rely on the total cost of the jug or bottle. Instead, get the per-gallon rate based on the actual per gallon rate and the gallon consumption. In other words, base your selection on which product gives you the best value.
Typically, a 2.5-gallon container can cost anywhere from $10 to $30. So there’s quite a bit of variety in terms of pricing.
How to Select DEF Fluid?
You should pay attention to the brand and specification of the DEF, whether it meets them or not. It should meet the ISO 22241 specification, which is an industry-standard. There are other standards and certifications as well, as the API certification.
Of course, as discussed, you should also look into the price, as high DEF consumption can lead to higher overall running costs. If you don’t have budget constraints, you could go for a high-priced one.
Also, take into consideration how much DEF your vehicle’s tank holds. While it automatically keeps some as a reserve, the last thing you need is running out of DEF on the freeway or runway.
Best DEF Fluid for Cummins
The top best product [hide]
Prestone Command Diesel Exhuast Fluid
While it’s a little pricey, it does keep the consumption around 3 percent. In other words, it will make up the costs over time by using slightly less DEF as compared with cheaper options with higher consumption rates. This is API certified and meets ISO 22241 requirements.
Peak BlueDEF Diesel Exhaust Fluid
Ford Motorcraft Diesel Exhaust Fluid
This is designed for Ford trucks which do a lot of hauling and towing. So if you need a RAM def fluid that supports such hardwork, perhaps Motorcraft is a good option. This one also meets the DIN 700071 requirements.
AdBlue® Diesel Exhaust Fluid
KleenDEF Diesel Exhaust Fluid
This does meet the ISO 22241 specification. It’s also one of the most affordable options, so you can save money if you buy in bulk. However, it’s not the easiest to add to the tank, but you can always use a funnel.
Conclusion
Your Cummins engine diesel truck requires quality DEF to run safely. Otherwise, the emissions can be dangerous. So always make sure that your vehicle has ample DEF in the tank. Your car will indicate when it needs a refill.
Since there aren’t that strict compatibility issues when it comes to DEF, you can choose from other brands. However, the main thing is purity, which cannot be compromised on.