Dexron iII vs vI Transmission Fluids: Which One To Chose?

Dexron is a popular name for a group of automatic fluid transmissions made by General Motors. However, there are a lot of Dexron variations with different model numbers that run in the Dexron series. You must have a clear concept on which of the Dexron fluids you should go for and its compatibility with your transmission.

The Dexron III vs Vi argument has lingered for a while. A lot of car users have different reasons why they prefer one of the products to the other.

Viscosity, performance, and engine compatibility, you wouldn’t want to put the wrong fluid into your transmission. 

Dexron VI is usually referred to as the updated version of Dexron III. But, are there other things that you should know before using any of them?

Well, this guide on Dexron III vs Dexron Vi will give you all the necessary information you need about this product to help you make a good choice.

Dexron iII – Short Overview

Dexron III is the 1993 release of GM’s transmission oil series. It is an inclusion of group 2+ base oils and additives. As a predecessor of the Dexron II, the Dexron III achieved improved friction stability, high-temperature oxidation stability, and material compatibility.

While the Dexron III scaled through with its amazing benefits, which include low-temperature fluidity, it had certain limitations. Some of which include; shear stability and fluid oxidation. The need to address these limitations produced multiple variations of the Dexron III.

These included the Dexron III (F, G, H). The versions were indicated with the defined letter and its license number. For instance: H-30001. This upgrade achieved better foam control, incorporated anti-shudder properties, and addressed friction maintenance needs. 

Gradually, Dexron III stood out as a universal option for automatic transmissions that had or didn’t have a controlled torque converter lockup clutch.

Although Dexron III phased out in 2011, earlier standards were reintroduced in the form of DEx/Merc, meeting the same standards as Dexron III.

Dexron vi – short overview

Dexron VI is the 2005 product of Ford and GM collaboration to develop a new 6-speed FWD transaxle (6T70/6F50). Ford produced the Mercon Low Viscosity fluid, and GM released the Dexron VI. Dexron VI boasts a lower viscosity level. 

Its lower and more stable viscosity level enhances the pumping efficiency of the transmission and the fluid stability. Compared to the Dexron III, the Dexron VI is thin. So it is essential to maintain its viscosity without allowing it to thin out. 

This is done by accompanying it with high-quality formulations and shear-stable specifications. 

Speculations have it that the Dexron VI is also backward compatible with Dexron III, but with only the H and G versions. However, the comparison surely has helped us conclude that they are not compatible and might work as a perfect fit for your transmission.

If your transmission has a default requirement of Dexron III, you should try to stick with it. Dexron VI was first used in 2007 6T70/6T75 transaxles and the 2007 6L80 transmission. 

Dexron iII vs vI: Key difference & Comparison

FeaturesDexron IIIDexron VI
ViscosityHigher ViscosityLower Viscosity
DesignSemi-synthetic premiumFully Synthetic
CompatibilityYou cannot use Dexron III with Dexron VIYou cannot use Dexron VI with Dexron III
Oxidation StabilityLesser Oxidation stabilityImproved Oxidation stability
Frictional StabilityLesser Frictional StabilitImproved Frictional stability

1. Viscosity

Dexron III has a viscosity rating of 30.2. This is higher than the viscosity level of Dexron VI, as it has a viscosity rating of 26. This includes Dexron VI maintaining a max of 6.3 cSt at 100°C  and 7.5 cSt at 100°C for Dexron III. A lower viscosity level in Dexron VI makes the fluid thin. 

This is an advantage to the Dexron VI because it is easier to move freely into all parts of the transmission. This goes as far as achieving a low-temperature fluidity that allows Dexron VI to maintain a high level of fluidity, even at low temperatures. 

There is a great impact on the level of protection achieved on the internal components of the engine. The low viscosity of Dexron III also helps to achieve fuel efficiency in the system.

2. Durability

A lot of times, you will need to consider how often you will need to change your transmission oil. This is determined by the shelf life of the transmission oil. Dexron VI has a longer shelf life than Dexron III. 

This keeps the transmission oil in good shape over a long period. Dexron VI can serve as cost-effective transmission oil because you wouldn’t need to always change the transmission oil.

3. Oxidation Stability

Dexron III has a record of maintaining high-temperature oxidation stability. Nevertheless, Dexron VI offers improved oxidation stability. This usually determines how much intense work these fluids can handle before breaking down or deteriorating.

4. Frictional Stability

Dexron 3 has improved frictional stability. There is stability in dynamic friction with Dexron III compared to older versions of the Dexron series.

5. Usage

Dexron VI was found in most old and new transmissions. However, the Dexron III was a preferable choice for a lot of commercial vehicles with automatic gearboxes and power steering. Dexron VI was a household name and the transmission choice for most 2006 automatic transmissions.

6. Overall Benefits

Certain benefits differentiate these transmission oils from the others. Dexron III has better material compatibility, while Dexron VI has improved shear stability, anti-wear protection, and foam resistance.

dexron 3 vs dexron 6: key Similarities

1. Transmission Oil

Dexron III and Dexron VI- both are automatic transmission fluids. Although they are designed to meet different specifications, they follow the same mechanism. While there are collective differences in their anti-wear, lubricating, anti-foam, maintenance, and preventive measures, they achieve the same aim.

2. Synthetic transmission Fluids

Dexron VI and Dexron III are not regular oils, they are synthetic transmission fluids. They have a long shelf life and beat oxidation and shear standards. 

These GM products collectively work to lubricate the bearings and internal components of the car. 

With the provision of hydraulic pressure and sustenance of friction, these transmission fluids work to keep your transmissions cool.

3. Design

These transmissions maintain the same color and a similar liquid volume. Running in a gallon of approx. 3.8L, there are just slight differences in the content of the container. Both GM transmission fluids have a red color. 

The design of Dexron III and Dexron VI targets improving fuel economy and prolonging the life and validity of the transmission. More importantly, their structural design makes both of them highly heat resistant.

Dexron iii and VI: Which One to prefer?

This is the right time to decide which one you should prefer between Dexron III and VI. You don’t need to get confused over deciding between Dexron III vs Dexron VI. It all boils down to why you need any of them. 

If you need a cheaper product, then you should go for Dexron III. On an overall scale, Dexron VI is a better choice than Dexron III, with advanced qualities. From the inclusion of longer shelf life to the numerous benefits that Dexron comes with, it is a better choice for your transmission.

If you need a top-notch transmission oil with a guarantee for high performance, you should go for Dexron VI.

frequently asked questions (FAQs)

Can I use Dexron VI instead of III?

Yes, you can. The production of Dexron III ceased permanently at the end of 2011. From GM to other popular manufacturers, there was a loud echo to permanently adopt the use of Dexron VI instead of III. 

This is because the Dexron VI can also function perfectly in older automatic transmissions or as a substitute for Dexron III. It is also important to note that Dexron VI is also backward compatible and can work in place of Dexron III.

Is DEXRON-vi full synthetic?

Yes. Dexron VI  is full synthetic transmission fluid. Being designed, licensed, and approved by General Motors(GM), it matches and exceeds the full requirements of the company and is full synthetic transmission fluid.

It features similar characteristics to a full synthetic transmission fluid such as fuel economy, exceptional thermal capacity, and durability.

Is Dexron 3 transmission fluid synthetic?

Dexron III wouldn’t pass as full-synthetic transmission fluid. It contains some group 2+ base oils and additives. Although Dexron contains a list of friction modifiers, it is not considered a full-synthetic transmission fluid like Dexron VI. 

However, Dexron 3 is not a conventional fluid, but a synthetic transmission fluid. 

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Considering the oxidation fluidity and low-temperature fluidity in Dexron VI, it will perform well even at low temperatures. Dexron VI will meet your expectations. 

Nevertheless, if your owner’s manual comes with a description that indicates that you should use Dexron III, we will advise that you stick with that. You must not also make the mistake of trying to mix Dexron III and Dexron VI for usage; they should act as independent components. 

Once more, the choice is yours. Dexron III and Dexron VI are popular brands, with exceptional records. Consider your preferences, budget, and transmission requirements, and choose accordingly. 

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Mahir Ahmed


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