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Which diesel exhaust fluid is best?

When you have a diesel vehicle, besides adding fuel, you need to add diesel exhaust fluid. Diesel-powered vehicles require diesel exhaust fluid to reduce engine emissions, making them less harmful to the environment and safer to drive.

The best diesel exhaust fluid meets the Environmental Protection Agency’s standards and is free from impurities. Valvoline’s Premium Blue Diesel Exhaust Fluid is a top choice because it is compatible with all selective catalytic reduction systems and meets the EPA’s near-zero nitrogen oxide emissions levels standard.

What to know before you buy diesel exhaust fluid

What is diesel exhaust fluid?

In 2010, the EPA created stricter standards for diesel vehicle emissions to reduce nitrogen oxide emissions and particulate matter. Diesel exhaust fluid is the key to making that happen. Diesel exhaust fluid is deionized water and urea (a substance produced from synthetic ammonia and carbon dioxide). A reservoir separate from the fuel tank holds the diesel exhaust fluid and injects it into the exhaust system to control specific emissions. Inside the exhaust system, the diesel exhaust fluid vaporizes and reacts with oxygen and nitrogen oxides to produce nitrogen and water vapor.

Diesel exhaust fluid is not a fuel additive

It is critical to know that diesel exhaust fluid is not a fuel additive, so you must never add it to the fuel tank. Since diesel exhaust fluid is heavier than diesel fuel, it will sink to the bottom of your tank and may damage the entire fuel system of your vehicle. If you find diesel exhaust fluid accidentally added to your fuel tank, it is recommended you do not even start the engine. Instead, call for service immediately to try and prevent costly repairs.

Can you drive my vehicle without diesel exhaust fluid?

Modern vehicles have a failsafe feature that engages if you ever run out of diesel exhaust fluid. This feature renders your vehicle near useless as it restricts movement to below 5 mph. This is why it is vital to keep an eye on your diesel exhaust fluid gauge and pay attention to those 500-mile, low-diesel-exhaust-fluid alerts.

What to look for in quality diesel exhaust fluid

Meets or exceeds EPA standards

For diesel exhaust fluid to meet EPA standards, it must contain very few impurities. These impurities can damage your vehicle’s selective catalytic reduction system. If you come across a brand of diesel exhaust fluid that does not indicate that the product meets the quality standards for diesel engines, ISO 22241, do not purchase this item.


If it is an emergency, you may only be interested in 1 gallon of diesel exhaust fluid. In most instances, however, you should purchase at least 5 gallons. This is a wise strategy because diesel exhaust fluid usually is more affordable when you buy larger quantities, and you never want to be caught without diesel exhaust fluid.


While it is possible to use a funnel to add diesel exhaust fluid to your vehicle, it is far better to use a nozzle specifically designed for adding diesel exhaust fluid to your vehicle. Ideally, the diesel exhaust fluid you are considering should contain some sort of a nozzle.

How much you can expect to spend on diesel exhaust fluid

The cost of diesel exhaust fluid can range from 50 cents per gallon to as much as $12 per gallon. While brand recognition and the retailer play a part, the larger the quantity you purchase, the lower the price-per-gallon tends to be.

Diesel exhaust fluid FAQ

What is the shelf life of diesel exhaust fluid?

A. The shelf life of diesel exhaust fluid is dependent on temperature. The higher the temperature, the shorter the shelf life. If you store your diesel exhaust fluid in a location that never exceeds 75 degrees Fahrenheit, it may last anywhere from 18 to 24 months. Once the temperature exceeds 86 degrees, however, you have a maximum of 12 months of storage. Also, it is best to check the container for the expiration date to know exactly how long the product should last. Additionally, suppose you add diesel exhaust fluid to a vehicle not regularly driven. In that case, it is recommended that you drain the diesel exhaust fluid after a maximum of 12 months and refill it with fresh fluid.

How many miles will you get from a gallon of diesel exhaust fluid?

A. Depending on your vehicle, you will go through roughly 1 gallon of diesel exhaust fluid every 200 to 300 miles.

How do you know when you need to add more diesel exhaust fluid?

A. While adding diesel exhaust fluid is an additional vehicle maintenance task for diesel vehicle owners, the good news is, your vehicle will tell you when to add it. Like a gas tank, some users prefer to top it off before it gets too low, while others wait for a warning. If you want to top it off before a trip, that is fine. Once you get to less than 500 miles, your vehicle will let you know it is time to add the fluid, so you never have to worry about running out.

What’s the best diesel exhaust fluid to buy?

Top diesel exhaust fluid

Valvoline Premium Blue Diesel Exhaust Fluid

Valvoline Premium Blue Diesel Exhaust Fluid

What you need to know: This diesel exhaust fluid from a trusted brand comes in a two-pack of 2.5-gallon containers, making it suitable for roughly 1,000 miles depending on your vehicle’s miles per gallon.

What you’ll love: This diesel exhaust fluid meets the EPA’s near-zero nitrogen oxide emissions levels, and it is compatible with all on- and off-highway selective catalytic reduction systems. Valvoline’s diesel exhaust fluid is certified by the American Petroleum Institute and meets ISO 22241 specifications. It is manufactured using dedicated equipment to ensure the product is contaminant-free.

What you should consider: If you don’t need much, this two-pack may be more than you want to purchase at one time.

Where to buy: Sold by Amazon

Top diesel exhaust fluids for the money

Blue Def Diesel Exhaust Fluid

Blue Def Diesel Exhaust Fluid

What you need to know: This two-pack of diesel exhaust fluids is a popular brand offered at a reasonable price to provide solid value.

What you’ll love: This stable, colorless and odorless formula meets ISO 22241 standards for purity and composition. It is certified by the American Petroleum Institute, and it is designed to be used in a selective catalytic reduction system to reduce the levels of nitrogen oxide emissions.

What you should consider: A few users had issues with this product dribbling and spilling while pouring.

Where to buy: Sold by Amazon and The Home Depot

Worth checking out

ACDelco Diesel Exhaust Fluid

ACDelco Diesel Exhaust Fluid

What you need to know: If you only need a little bit of diesel exhaust fluids, this 1-gallon container will do the trick for GM vehicles.

What you’ll love: This product meets GM Original Equipment specifications for use in all GM vehicles that have a selective catalytic reduction system. It is manufactured from high-purity urea and deionized water that contains no chemical additives, and purchase includes a vented nozzle to facilitate pouring. 

What you should consider: The price-per-gallon of this diesel exhaust fluid is a bit higher than what you would pay for larger amounts.

Where to buy: Sold by Amazon

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Allen Foster writes for BestReviews. BestReviews has helped millions of consumers simplify their purchasing decisions, saving them time and money.

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