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Oil & Fluids

SuperTech DEF vs Blue DEF: Is There Really Any Difference?

supertech def vs blue def
Last Updated on Aug 16, 2023 By Lillian Kazmierczak

All DEFs are manufactured following the same ISO 22241 specifications that require the fluid to be between 31.8% to 33.2% urea with a maximum of 20 mg/kg of insolubles. It also states the amount of every mineral to be used; i.e., .2 – .5 mg/kg as well as the alkalinity of the water.

So, they all are the same thing –  no matter the brand. Well, there could be minor quality differences among the different manufactures but not so significant that’ll have an impact on your engine’s emission level.

When talking about the Supertech DEF vs Blue DEF debate, we’ll mainly focus on those minute differences. But remember that since they all perform the same, you can’t go wrong even with the cheaper options.

The pumps at truck stops have the cheapest stuff that’ll save you money.

SuperTech DEF vs Blue DEF: How Do They Differ?

Comparing factors  Supertech DEF Blue DEF
Manufacturer Supertech (Walmart Dealer) Old World Industries
Performance Good enough A bit better
Fuel economy Good enough A bit better
Mileage Less More
Certification API ISO & API
Packaging Gallon Box
Spout Flimsy and short Standard size
Price Less expensive More expensive


SuperTech is a house brand of Walmart. They’re a familiar name in the market but with a bad reputation for having compromised product qualities.

On the other hand, Old World Industries is the company that manufactures Blue DEF. This is a well-known and more reputable brand as their products are known to meet higher standards that get appreciation from many experts.


We’ve heard of many complaints about foul odor coming out from Supertech DEF, causing some users to even return their purchases to the stores.

However, we’re yet to hear the same about Blue DEF, which means there’s little or no chance that you’ll have odor issues.


There is no such widespread report of engines shutting down or having significant issues after using the SuperTech DEF.

But some experienced error codes and warning lights shortly after adding this fluid from Supertech. This can be an indication of poor-quality fluid as these problems mainly arise due to clogs in the spray mechanism.

On the other hand, Blue DEF users never reported any such issues, which clearly ensures the higher quality of their product.


Although Walmart DEF doesn’t fall short in performance as there are no such reports, Blue DEF is considered a better-performing fluid because it meets both ISO and API standards.

It will also provide better engine power compared to Walmart DEF.

Fuel economy

Supertech DEF is strong enough to give you better fuel economy and efficiency. Likewise, Blue fluid will also undoubtedly provide the same (or even better) results.


Although Blue DEF will surely give you better mileage, Supertech will not disappoint you too as 2.5 gallons of Supertech DEF can go around 700 miles.


The main purpose of the diesel exhaust fluid is to reduce the toxicity of exhaust emissions and leave less nitrogen oxide in the environment by transforming it into ammonia and vapor.

As stated above, there are governing bodies to ensure that all the DEF products available in the market do this the most effective way.

Both fluids come with reliable certifications and do their job perfectly. Walmart DEFs are certified by the American Petroleum Institute (API) while Blue DEFs come with both ISO 22241 and API certifications.

Since Supertech doesn’t boast of both certifications and their API certification tag is barely visible, many have doubts in their quality. But we assure you that you’ll be fine with their products for sure.


Although this sounds awkward, some users found broken seals in Supertech DEFs in Walmart as they come in plastic gallons.

It is really a concerning factor as you don’t know if your product is tempered. There are even reports that someone found water instead of the fluid in the container!

However, you won’t have the same issue with the Blue DEF as it comes with a box container and gives more assurance that no one has mixed anything with the fluid.


The flimsy, flexible, and short spout that comes with the Walmart DEF makes it inconvenient and sometimes challenging to pour the fluid into the vehicle, especially from the wrong side. You may also spill and waste some of your valuable fluid.

On the other hand, Blue DEF has a standard-sized spout, which makes the pouring an easy task.


It is evident that the only reason people use Supertech DEF is because of its easy availability and affordability.

You will get a 2.5-gallon Supertech DEF for $8 to $12, which is comparatively almost 5$ less than the Blue DEF as the price range for Blue DEF is $15 to $20.

Pros and Cons of Supertech DEF


  • API certified
  • Reliable
  • Good performance
  • Better mileage
  • Fuel efficient
  • Affordable
  • Has OEM approval on all SCR-equipped engines
  • Easy to return


  • May have compromised quality
  • Small spout
  • Possibility of temperaments

Pros and Cons of Blue DEF


  • ISO and API certified
  • Has OEM approval on all SCR-equipped engines
  • Better mileage
  • Better quality
  • Fuel efficient
  • Standard sized spout
  • More reliable
  • Package can’t be tempered


  • Expensive

Supertech DEF vs Blue DEF: Which One to Choose?

No one would want to damage the engine of a 100,000-dollar truck just to save $5 or $10, right?

There are concerns about Walmart products because there were some incidents that gave their products a bad reputation. For instance, in 2019 some issues led to the recalling of Supertech DEFs when a truck dealer refused to honor the warranty on a diesel truck because of using Supertech DEF.

They claimed that since SuperTech didn’t meet ISO standards, the warranty would be void.  Although it was more of a local problem with that particular store than a general one, some people still remember that and stay away from Walmart.

If you are one of them then you can go with Blue DEF. But remember, it will cost more while providing almost the same level of quality and performance.

It’s true that Walmart DEF doesn’t have ISO certification but they’re backed by API, which is enough to assure their quality.


1. Is Walmart DEF OK?

Ans: Yes, it is totally okay and will save you money since it’s cheaper. It’s API certified, which would not have been possible to achieve if it didn’t meet their standards.

2. Can different brands of DEFs be mixed?

Ans: Yes, you can mix certified DEF fluids from different brands but it’s better to fully empty your tank before you use a DEF from a different brand.

3. Should I keep my DEF tank full?

Ans: Yes, you should. Your engine power will de-rate if the DEF tank contains less than 5% of its capacity. But you’ll still have enough power to reach a nearby place to add refills. Try adding fluid to the DEF tank once for every 3 to 4 times of diesel refills.

4. Can I use expired DEF?

Ans: No, absolutely not. DEF fluids should only be used before expiration as they work fine for a certain period of time. Also, remember that an expired fluid can even damage your engine.

About the author

Lillian Kazmierczak

As far as I can remember, I would say I have been a car nut for my whole life. My father was a car dealer who used to change and repair his cars himself. This gave me the opportunity to get around all sorts of cars and get my hands dirty repairing vehicles from an early age.

A great fan of Japanese quality and German preciosity, my deep passion lies in older models that I believe have a flair that takes me back to my childhood! I also love their extraordinary durability and reliability when compared to today’s modern models.

When not out taking a ride, I enjoy socializing with fellow motorheads online and consuming any car facts and figures I can get my mind on!

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