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Best DEF Fluid: What To Buy & Why It Matters
Diesel exhaust fluid (DEF) plays a crucial role in modern diesel engine emissions systems, from workhorse half-ton pickups to the numerous fleets of semi-trucks that transport America’s freight.
Supplying your vehicle or fleet with high-quality DEF ensures its daily performance and longevity, minimizing the risk of unplanned downtime, costly repairs, and lost revenue. Below, we’ve compiled a list of the best DEF fluid to keep your fleet running smoothly.
Why Is DEF Fluid Important for Diesel Performance?
Per the Environmental Protection Agency (EPA), diesel engines must meet strict emissions standards.
Modern diesels achieve compliance with these regulations by integrating a selective catalytic reduction (SCR) system, which requires diesel exhaust fluid (DEF) to convert harmful nitrogen oxides (NOx) into nitrogen and water vapor. Specifically, DEF requires a specific urea concentration to effectively meet emissions standards and reduce the diesel engine’s environmental impact.
Failure to meticulously monitor and maintain DEF levels can have a serious impact on any fleet. Diesel exhaust fluid is also a consumable, similar to motor oil, transmission fluid, brake fluid, and power steering fluid, and must be replenished periodically.
Issues with the SCR system — including a lack of DEF or inferior-quality DEF — can force the engine into limp mode, prohibiting the vehicle from performing as expected.
5 Best DEF Fluid Products for Your Diesel
The best diesel exhaust fluid for your diesel-powered vehicle is the one recommended by the owner’s manual or an equivalent.
Although DEF products must meet similar standards, choosing the best one for your application has a direct impact on your diesel engine’s lifespan. Below are some of the best DEF fluid products from the most trusted brands in the market.
1. BlueDEF by Peak
A quick search for diesel exhaust fluid typically returns Peak BlueDEF as one of the top products.
PEAK BlueDEF Diesel Exhaust Fluid meets or exceeds OEM and ISO 22241 specifications, with its triple-filtered formula that’s designed to prevent urea crystals from forming in your diesel’s SCR system. Speaking of, Peak BlueDEF is compatible with all diesel SCR systems, so you don’t have to worry about switching brands or products between diesel platforms.
2. Valvoline Premium Blue DEF
Known for its consistent quality and performance, Valvoline Premium Blue DEF offers reliable performance and wide compatibility with most SCR systems.
Like each of the diesel exhaust fluid products on our list, Valvoline’s Premium Blue DEF meets ISO 22241 standards, exceeds many OEM specifications, and bears the API certification mark. You can find Vavoline’s DEF at most retailers and auto parts stores.
3. SuperTech DEF
Diesel exhaust fluid from SuperTech meets API and ISO standards and occupies an affordable segment of the DEF market. Compatible with all SCR systems, SuperTech DEF is low-odor. It also typically comes in a conveniently designed jug featuring a handy pour nozzle.
4. BlueDEF PLATINUM
Although Peak’s BlueDEF gets the job done, the brand’s BlueDEF PLATINUM product goes a step further for even better results.
The advanced additives and synthetic urea content within this diesel exhaust fluid help maintain superior fuel economy and prevent urea deposits from forming within the SCR system. API certified, BlueDEF PLATINUM also meets or exceeds OEM and ISO 22241 standards.
5. Prestone Command DEF
If you’re looking for the best balance of price and performance, Prestone DEF stands among the top options.
Compatible with nearly every SCR system, Prestone’s diesel exhaust fluid features high-grade urea content that’s odorless and available in multiple quantities. In addition to delivering consistent performance and value, Prestone DEF also carries the API certification and meets ISO and OEM standards.
What Should You Look for in DEF Fluid?
Different variants of diesel exhaust fluid may serve the same purpose, but higher-quality DEF ensures your diesel engine’s optimal performance.
For example, the best diesel exhaust fluid should contain 32.5% urea, achieve 90% purity, have a specific gravity of 1.08-1.10 (at 60 degrees Fahrenheit), include 0.10% or less ammonia, and maintain an alkalinity between 7.5-9.5 pH when measured at 77 degrees Fahrenheit.
Use the following characteristics to determine the best DEF for your application:
- Purity: Diesel exhaust fluid must meet purity standards to earn the ISO 22241 certification and the API Diesel Exhaust Fluid Certification Mark.
- Compatibility: Any DEF you choose should meet or exceed OEM specifications for best results.
- Brand reputation: Purchasing DEF manufactured by trusted brands capitalizes on their expertise to the benefit of your diesel engine.
In a discussion of the qualities of the best DEF, the topic of box DEF vs. DEF available at the pump often pops up.
Boxed diesel exhaust fluid allows you to keep a supply of emergency DEF on hand, but it’s usually more expensive than pump DEF and requires careful monitoring and storage. Topping off your diesel’s DEF tank at the pump offers a certain convenience, yet availability varies.
Alternatively, purchasing DEF from a trusted supplier can help you secure a preferred quality, availability, and price. Most DEF suppliers also offer supportive services to ensure safety and compliance. For example, Cadence provides monitoring capabilities for customers who purchase DEF in bulk.
High-Quality DEF Fluid From a Trusted Source
Cadence offers a broad range of superior DEF solutions available in several quantities, ranging from individual drums to bulk volumes. We’ve cultivated partnerships with trusted manufacturers to bring you the highest standard in diesel exhaust fluid and related products.
Contact us at 336-629-2061 today to learn more about purchasing DEF in quantity and how we deliver value at every turn.
Sources:
Diesel Exhaust Fluid (DEF) | API
PEAK BlueDEF Diesel Exhaust Fluid | Old World Industries