Emma Davies
Updated on January 23, 2023
Transmission fluid is a crucial part of keeping your automatic transmission system running efficiently and it’s essential you choose the best one to keep your vehicle running smoothly. Over time the Dextron brand has gained considerable credibility to become one of the trusted names in the industry, but what is the difference between Dexron 3 vs Dexron 6?
You may not visually notice that much difference between these two transmission fluids, but they are both better suited to separate vehicles to provide better friction stability and performance in high and low temperatures.
The Dexron 3 fluid is a thicker synthetic base transmission oil with less reactive friction stability in comparison to the Dexron 6 fluid which is fully synthetic and has thermally stable friction durability in a thinner and longer-lasting formula. We would choose the Dexron 6 as it has the ability to increase your engine’s fuel efficiency, better mileage, and smoother transmission.
Let’s take a closer look to see which of the Dexron 3 vs Dexron 6 transmission oils are best suited to your vehicle’s needs.
Dexron 3
Dexron III was released in 1993 from GMs transmission oil series and is part of the group 2+ base oils and additives that have improved friction stability, material compatibility, and high-temperature oxidation stability compared to Dexron 2.
It has great benefits such as low-temperature fluidity but there are some limitations such as the shear stability and fluid oxidation that were addressed in the Dexron 4 release. Dexron 3 stood out as a great universal option for transmissions that didn’t have a controlled torque converter lockup clutch.
The Dexron 3 was phased out in 2011 in favor of the newer versions that were released with a longer shelf life and variety in viscosity.
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Dexron 6
Dexron 6 came from the 2006 collaboration of Ford and GM to create a transmission fluid for their new 6-speed FWD transaxle. Ford made the Mercon Low Viscosity Fluid, and Dexron created 6 as their lower viscosity level.
The lower and more stable viscosity means the transmission pumping and fluid stability are much thinner. It can maintain its viscosity without the issue of thinning out thanks to the high-quality formula with shear-stable spec.
This transmission fluid is thinner and fully synthetic unlike Dexron 3 and features better oxidation and frictional stability and as they have worked to improve the performance over the years.
Prices pulled from the Amazon Product Advertising API on:
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on [relevant Amazon Site(s), as applicable] at the time of purchase will apply to the purchase of this product.
Dexron 3 vs Dexron 6: Differences
| Dexron 3 | Dexron 6 | |
| Viscosity | High viscosity | Lower viscosity |
| Design | Semi-synthetic | Fully synthetic |
| Compatibility | You cannot use Dexron 6 | You cannot use it with Dexron 3 but it can be used as an alternative |
| Features | Thicker consistency Oxidation stability Better friction stability | Anti-wear protection Anti-foam control Extra protection |
Viscosity
The viscosity of any fluid and oils in your vehicle will play a huge part in its performance capabilities as the thinness and thickness need to be the right level to resist heat and work well, but it can’t be too thick so it cannot reach all areas of your parts.
The thickness of the Dexron 3 oil led to difficulties in its ability to reach all components and work correctly which is where the Dexron 6 became more popular as it runs through every part of the vehicle’s automatic transmission system and works excellently.
Cold Temperature Performance
If you live in an area with particularly cold weather then you’re going to want to make sure all the fluids and oils in your vehicle are going to continue to flow against the freezing temperatures and provide protection and performance as you would expect.
The Dexron 3 transmission fluid is better suited to resisting freezing temperatures and contains technologies so your oil can work better inside and offer greater performance driving.
The Dexron 6 oil can get concentrated and increase the density and your transmission system can lose power and need fluid replacement.
High Temperature Performance
Heat resistance is a key factor for any oil or fluid in your vehicle as it can impact the way it works when your engine is particularly hot, or if you’re in a high-temperature climate.
The Dexron 6 and Dexron 3 are both incredibly heat resistant and prevent friction that can damage your systems and if this is a huge consideration for you then both are great choices, however, the Dexron 6 does have more modern technology and advancements so you can expect better performance.
Can You Mix Dexron 3 and Dexron 6?
Replacing and mixing transmission fluid is not recommended as they are ATFs that change, and when you mix them they use different components that may not mix. Dexron 6 can replace Dexron 3, as they are both suggested for the same vehicles and the upgrades that come from the newer blend could be a great performance boost in your vehicle.
Many users consider using Dexron 6 as a replacement for Dexron 3 as there are so many upgrade options that protect you from rust, and corrosion, and give better control over oxidation and foam control than you wouldn’t get from the Dexron 3.
There is also the benefit of improved fuel efficiency which is going to give a smoother running capacity and ensure a healthy transmission flow that can keep your automatic transmission running for a longer lifespan.
Dexron 3 vs Dexron 6: Which Is Best?
Deciding between the two transmission fluids is largely down to personal choice and if you are using a newer or older vehicle with an automatic transmission. Dexron 3 has a lower shelf life and will require more frequent change intervals, whereas the Dexron 6 has a much higher level of advanced technology as it is much newer.
The Dexron 6 contains anti-foaming and healthier transmission flow and can improve your fuel efficiency by giving you a smoother running capacity and better mileage, so in our opinion, Dexron 6 is the better choice for your vehicle.
| Dexron 3 | Dexron 6 | |
| Pros | Better suited for lower temperatures Friction durability High-temperature protection | Improved oxidation and frictional stability Better fuel efficiency Anti-foaming system Longer shelf life |
| Cons | Less oxidation stability Less frictional stability Shorter shelf life | Lower viscosity Thinner Less suited to lowertemperatures |
Conclusion
Dexron transmission fluids have seen plenty of changes over the years to keep up with advancements and provide the best performance possible.
This is reflected in the Dexron 6 transmission fluid as it stands out from the rest with a huge range of perks including longer shelf life and better frictional stability when compared to Dexron 3 making Dexron 6 our winner.
But do not discount Dexron 3 as it has superior temperature protection this older formulation is still a winner for many today.
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