6 Problems With Walmart DEF Fluid (Explained for Beginners)

Walmart DEF Fluid Problems

Walmart’s house-brand DEF – SuperTech – is offered at a considerably lower price.

While this is a good thing, it does raise some issues.

The diesel exhaust fluid might have some quality control issues, and some customers have complained of boxes with broken seals. Also, Walmart SuperTech DEF doesn’t have the ISO standard certification.

Read on to learn more about some of the common problems with Walmart DEF.

Quality Control Issues

Walmart goes through SuperTech quite easily, so you’ll likely get fresh DEF on the shelves. 

That being, it is not completely uncommon to see customers returning the diesel fluid owing to one quality control issue or another.

One of the complaints is that Walmart DEF has an odd smell.

And to show that this is a common problem, many Walmart managers aren’t surprised when this happens. 

They’ve probably seen it a dozen times.

The good thing is that exchanging the DEF or even getting a refund isn’t complicated. 

In most cases, the managers will gladly exchange the defective product with another.

Safety Seal Tempering

Seal tempering is something you need to be aware of you are looking to buy Walmart SuperTech DEF.

There have been unsubstantiated reports of the product being filled with water.

In Walmart’s defense, this is probably not the company’s fault. Instead, it is likely the case of someone filling the container with water before returning.

Of course, DEF is essentially water mixed with urea. 

But there’s more to it!

The water and urea must be mixed in precise ratios that meet the diesel industry standards.

Merely adding water to urea can cause serious damages to diesel-fired vehicles. 

Bottom line: Do not use SuperTech (or any other DEF product for that matter!) if the tamper seal is broken.

Possible Clogging of SCR

Although it is not common for the Selective Catalytic Reduction (SCR) system to clog due to the use of Walmart DEF, it is definitely a more serious problem.

Some users say that using the product in their truck threw up a warning light or error code.

Usually, this indicates that there is something wrong with the DEF system. This has something to do with the fluid clogging the spray mechanism (SCR). 

Again, these may be isolated cases and might not be peculiar to Walmart DEF. 

In any case, you should be aware that there is a slim chance of getting your engine’s SCR clogged. 

And if that ever happens, the DEF system will require service or even a replacement.

Short Spout Can Cause Spillage 

Okay, a short spout might not be a big issue and definitely doesn’t make a lot of difference unless your DEF tank is on the passenger side.

Walmart DEF container is designed with a flexible spout that can be a bit inconvenient when you pour the fluid into a tank on the “wrong” side.

This can cause spills. 

Although the product is a lot cheaper than most other options from other companies, you don’t want to be wasting your diesel exhaust fluid.

No ISO Certification on DEF Label

Perhaps the most common reason many people tend to avoid Walmart DEF is that the product seems to lack an ISO certification.

And the operative word there is “seems.”

This is not a problem with the product itself but with the general perception of Walmart’s diesel exhaust fluid.

Here’s a case in point.

In 2019, some issues led to the recall of SuperTech. 

It was somewhat connected to a RAM truck dealer who didn’t honor the warranty on a diesel truck because the truck owner used Walmart DEF.

The claim was that SuperTech doesn’t meet the ISO standard since the product label doesn’t indicate that it meets the ISO 22241 standard.

To make a long story short, it turns out the recall was a local problem with that particular Walmart store and not a general one. 

Unfortunately, many internet forums had already run wild with the “recall” story. Luckily, a good number of customers researched a little bit and found that the problem isn’t widespread.

In fact, there is no mention of the recall on Walmart’s product recall site.

But here’s the meat of the matter.

SuperTech doesn’t have an ISO certification, and that has caused a lot of confusion, especially for would-be users.

No one wants to risk damaging a $100,000 truck just to save less than 10 bucks.

In other words, many people avoid Walmart DEF because using low-quality fluid is not something you ever want to do with your diesel engine.

For beginners, it is important to clarify that SuperTech has the American Petroleum Institute (API) DEF certification.

Indeed, the Walmart DEF label doesn’t specifically show the ISO 22241 standard. But the diesel fluid must meet the standard, or else it won’t have the API DEF certification.

Easily Confused Date Code 

The date label on the DEF container or box is another problem that can easily lead to confusion.

For many first-time users, it can be tricky to figure out whether the date code on the DEF container refers to the production date or expiration date.

To make things worse, the date label on Walmart DEF is not in the Julian format, which many people expect with these types of products. 

While this may seem like a minor issue, you might end up buying an expired product if you get the dates mixed up. 

For the avoidance of doubt, the date code on Walmart SuperTech DEF refers to the manufacture date. 

Keep in mind that DEF products should be used within one to three years of production. 

The longer it stays, the more the fluid is exposed to hotter temperatures. And that can make it go bad.

Summary of Walmart SuperTech DEF Pros and Cons

Here’s a quick rundown of the pluses and minuses to keep in mind if you are looking at buying Walmart’s SuperTech diesel exhaust fluid.


  • Walmart DEF is readily available 
  • Ease of return 
  • SuperTech is fresh on Walmart shelves 
  • Very affordable compared to the same product from other companies
  • Has the American Petroleum Institute (API) DEF Certification


  • Possible SCR Clog
  • Quality control issues
  • Confusion over ISO certification
  • Seal tempering
  • Spillage due to short container spout 
  • Confusion over date code 

What’s the General Review for Walmart DEF Fluid 

The overall feel from Walmart DEF users shows that the product is generally safe. 

Of course, there are a few genuine complaints and many unsubstantiated claims.

But regardless of the generally positive reviews, it is best to avoid using Walmart SuperTech DEF in your rig if doing so will void your truck’s warranty.

While the diesel fluid might not damage your engine, it is better to err on the side of caution than lose several hundred dollars in warranty!

Final Thoughts 

A lack of ISO certification on Walmart DEF might make many people think the product is low quality.

Combine that with its significantly lower price, and it is easy to see why many beginners would want to avoid using SuperTech.

However, the product has an API certification. This makes it a certified diesel exhaust fluid.

Of course, you might have the occasional quality control issues, broken seals, and a few other hiccups. 

But that’s not peculiar to Walmart. 

Overall, you will be saving a few bucks with Walmart DEF and it is very safe to use the product in your diesel engine.

You can see this article for more information about the difference between engine oil and motor oil.

Is Engine Oil the Same as Motor Oil? (These Products Tell You Answer)


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