Best Transmission Fluid for 4r100 + (Which Should You Buy)

Transmission fluid is an essential part of having a well-functioning transmission. Not only does it ensure that the insides of your transmission are well-lubricated, but it also boosts performance and greatly increases the lifespan of your transmission. 

You don’t just get a bottle of this magic stuff for all cars, however. Transmission fluid is very specific in its features and it’s extremely important that you choose the right one for your vehicle’s transmission. Choosing the wrong transmission fluid can be fatal for your transmission — and repairs aren’t cheap! When just starting out with your decision of which automatic transmission fluid to use, it’s a good idea to do some research (like reading our article) so that you can make an informed choice. Once you’ve found the right transmission fluid, it’s just a matter of sticking by it for years!

Top 5 Best Transmission Fluid for 4r100

Apart from just manual and automatic transmission fluid, there are other specifications as well that can make it difficult to find the right one for your vehicle. 

That’s why we’ve put together this article — we’ve only listed transmission fluids that work well for your 4r100, and we’ve only included the best! Keep reading to find out our top pick and detailed pros and cons for each product so that you can make an informed choice to take care of your 4r100 transmission. 

#1- Genuine Ford XT-5-5QM MERCON-V Automatic Transmission and Power Steering Fluid

Ford Genuine XT-5-5QM MERCON-V Automatic Transmission and Power Steering Fluid - 5 Quart

We’ve ranked the Genuine Ford Genuine Ford XT-5-5QM MERCON-V Automatic Transmission and Power Steering Fluid as our top pick for multiple reasons. It’s approved and sponsored by Ford, which means that your F-series truck is in good hands. It’s also known for being one of the best options out there in the market. This premium automatic transmission fluid is actually recommended by the Ford Motor Company so you can safely use it.

If you’ve purchased a new 4r100 transmission, you’ll want to use this transmission fluid since it will likely keep your warranty valid. 

The Motorcraft Mercon V has everything you need in transmission fluid. It’s made with hydro-processed base oils that lubricate the transmission components. The premium quality transmission fluid has high-viscosity, and remains fluid even at extremely low temperatures. This makes it suitable for vehicles in very cold climates as well. 

You’ll also experience the specially added performance additives. These additives provide valuable capabilities to the transmission fluid, like resistance to oxidation as well as great shifting characteristics among a large range of temperature points. 

You won’t have to worry about the transmission fluid getting gummy or leaving behind any traces of sludge. It is also anti-corrosive in nature, protecting your transmission from ever getting rusted or corroded. 

Finally, the reason why the fluid is bright red is so that you can easily detect it in case of an unexpected leak. It can be very dangerous to have a transmission fluid leak, so this feature is definitely a bonus. 


  • Manufactured by Ford
  • Model: XT-5-5QM
  • Weight: 9.35 pounds
  • Dimensions: 11.5 x 7.6 x 5.6 inches


  • Approved by Ford
  • Anti-corrosion
  • Bright Red for Detecting Leaks


  • Not as affordable as other brands

The Genuine Ford XT-5-5QM MERCON-V Automatic Transmission and Power Steering Fluid is great for anyone who wants to make a safe and reliable choice. While it might be slightly pricier in the long run, you can be rest assured that you’re using a transmission fluid that was especially made for your 4r100 transmission. 

#2- Valvoline Mercon V (ATF) Conventional Automatic Transmission Fluid

Valvoline Mercon V (ATF) Conventional Automatic Transmission Fluid 1 QT

This fully synthetic transmission fluid is an all-in-one solution for your transmission needs. It has plenty of special features and additives that drastically improve the performance of your 4r100 transmission. The Anti-wear technology is great for improving the overall durability of your transmission.

Even though Valvoline is not backed by Ford, there are many F150 and F250 owners who will use nothing but Valvoline Synthetic Automatic Transmission Fluid. 

The fully synthetic base oils prevent any kind of transmission breakdown. It is also formulated with a substance called low-friction modifiers. What this does is it directly improves the shifting: making it much smoother without any slippage or sudden shuddering. Overall, you’ll feel the difference in the drivability quotient of your vehicle after using Valvoline Full Synthetic Automatic Transmission Fluid. 

There are many different variants of Valvoline Transmission Fluid, so make sure that you select Mercon V and not any kind of Multi-Vehicle fluid since that can sometimes cause complications for your 4r100 transmission. 

The Anti-wear technology is great in improving the overall durability of your transmission. The blend of base oils also makes pouring easy, as well as providing a coating of film protection to the components of the transmission. This coating comes in handy when the transmission is heated to very high temperatures. 


  • Manufactured by Valvoline
  • Type: Mercon V
  • Weight: 1.91 pounds
  • Dimensions: 4.23 x 2.65 x 9 inches
  • Model: 822345


  • Affordable
  • Improves Shifting
  • Protects Transmission


  • Not certified by Ford
  • No anti-corrosion properties
  • Not colored for easy leak detection

If you’re not big on buying the branded version when a perfectly functioning alternative is available, you’ll like the Valvoline transmission fluid. It’s important to ensure that you’re using the Mercon V version for your 4r100 since this is compatible. This option is quite affordable and will definitely give you a tangible difference in your driving experience. 

#3- Castrol 03520C TRANSMAX DEX/MERC ATF

Castrol TRANSMAX DEX/MERC ATF, 1 Gallon, Automatic , Black

 The Castrol is recommended for Ford and General Motors vehicles that have power steering requirements for heavy towing and hauling. That’s because the Castrol Transmax ATF has really high temperature protection that ensures it is at the right liquidity at super high temperatures as well as almost freezing temperatures. 

Nobody would pay this much attention to transmission fluid if all it did was lubricate everything. The reason why we’re so particular about which transmission fluid goes inside the 4r100 is because it is quite literally liquid engineering. The best thing that you get about transmission fluid is buttery smooth shifting, and Castrol Transmax ATF is famous for this. 

It doesn’t matter how much mileage your vehicle has, you can still experience smooth shifting after using Castrol Transmission Fluid. This has enhanced friction durability that greatly extends the life of your transmission. All those drivers using a second-hand transmission? The right ‘tranny fluid’ just got that much more important!

Usually you should never mix transmission fluids. So far we’ve been showing you Mercon V fluids on our list since that is what the 4r100 requires. However, the Castrol Transmax ATF works for both Mercon vehicles as well as Dexron. Since it satisfies the requirements of both transmissions, you can safely use this for your 4r100 and experience great results. 

You’ll also get oxidation protection from the Castrol ATF: unlike other low-quality transmission fluids, you won’t have problems with the viscosity of this ATF. 

Since there are so many different Castrol ATFs, it’s extra important that you check the label carefully. Mercon LV is not compatible with 4r100. Initially Ford had recommended using Dex3. 


  • Manufacturer: Castrol
  • Model: 06818
  • Weight: 1.6 ounces
  • Dimensions: 9.5 x 9 x 7.8 inches
  • Type: Transmax Dex/Merc


  • Smooth Shifting
  • Affordable
  • Better gas mileage


  • Ambiguity around Type of Fluid
  • No anti-corrosion properties
  • Not colored for easy leak detection

Castrol isn’t just an affordable option when you’re trying to save some extra cash — it’s also one of the transmission fluids that give you a noticeable difference when shifting gears. Having said that, you do have to be extra careful when selecting the right transmission fluid since Castrol has so many different variants. There’s a big difference between Mercon V and Mercon LV so make sure that you read the labels carefully before purchasing or using the transmission fluid.

#4- Genuine Mazda Fluid MERCON-V Automatic Transmission Fluid

Genuine Mazda Accessories (0000-77-120E-05) MERCON-V Automatic Transmission Fluid - 1 Quart

Genuine Mazda Fluid is a great Transmission Fluid. A unique property of this transmission fluid is that it doesn’t deposit as sludge or have any kind of residue that’s difficult to clean. That makes it particularly useful when you have to do a full transmission flush.

It works for all vehicles that require Mercon-V and it provides superior performance. You get increased protection for the inner workings of your transmission, and like other good ATFs, you’re greatly increasing the life of your transmission by using this fluid. 

One of the special features of using Genuine Mazda Fluid is the protection that you get against low temperatures. If you’re living in an extremely cold climate location, ordinary transmission fluid can actually freeze inside your transmission when it is stationary! That is not good news at all and can cause serious damage to the 4r100 transmission. The Genuine Mazda Fluid does not pose this problem and will never freeze in cold climates. It retains optimum liquidity and viscosity. 

Not only does it provide super smooth shifting, but this automatic transmission fluid is actually specially formulated to protect against ‘shudders’. It’s quite concerning when your vehicle starts to shiver and shudder out of the blue, but it is actually the transmission that’s at fault when this happens. Using the right transmission fluid like the Genuine Mazda Fluid is great at preventing this from ever happening. 

The reason why the Genuine Mazda Fluid provides such good transmission performance is because it has highly specified features that finetune and optimize your transmission. For example, it boosts valve operation greatly. You’ll also see a big improvement in brake band friction. No more jerky brakes with this transmission fluid! Finally, it also helps with the torque converter and of course, superior gear lubrication. Both of these factor in towards buttery smooth shifting of gears while you’re driving, towing or hauling. 


  • Manufacturer: Mazda
  • Model: 0000-77-120E-05
  • Weight: 1.9 pounds
  • Dimensions: 8.7 x 4.3 x 2 inches


  • Great low temperature shifting
  • Anti-corrosion properties
  • Prevents transmission shudders
  • Affordable


  • Easily confused label

This transmission fluid is super affordable, especially once you consider all the features that it offers. It is almost half the price of some of the other transmission fluids that we’ve listed here. It works really well with the 4r100 transmission, provided that you purchase the right Genuine Mazda Fluid that is Mercon V and not Mercon M5 (which is a different type). Being extra careful while reading the label and purchasing the right type of transmission fluid can go a long way and save you a lot of money. 

#5- Triax Multi-Purpose ATF DEX III/MERC Synthetic Blend

TRIAX MP ATF DEX III/MERC, Synthetic Blend, Friction Optimized, No Slip, Flawless Shifting, -50 F Cold Flow (5 Gallon Pail)

The Triax Synthetic transmission fluid has SureShift technology. This greatly improves the shifting gear mechanism, making your heavy-duty vehicle feel much smoother during gear shifts. It also protects your vehicle against slippage, making sure that you never struggle with slipping gears.

The Triax Multi-Purpose Synthetic Blend ATF is one of the premium ATF options in the market. You get an exhaustive list of features with this automatic transmission fluid, and that’s probably why it’s used by large companies for fleet maintenance on Ford trucks and vans alike. If you’ve been using regular transmission fluid for years and are considering doing a flush and switching to a synthetic blend — then look no further!

Triax describes their shifting as ‘flawless’ and loyal users confirm this! Since smooth shifting is their focal point while formulating the transmission fluid, you’re guaranteed to get really good performance on this front while using the Triax Synthetic transmission fluid. 

On another note, if you happen to be struggling with slipping gears, it might be a sign that you’re not just using a sub-standard transmission fluid, but one that is not suitable for your transmission in the first place. Since the Triax Synthetic transmission fluid is compatible with the 4r100, you won’t have to worry about this issue. 

A unique factor that the Triax Synthetic transmission fluid offers is zero foaming. Foaming is something that many transmission fluids can be prone to, especially when quickly shifting temperatures. The Triax transmission fluid retains its liquidity and the optimum viscosity and won’t go through the bubbling and foaming. You don’t get the anti-foaming feature in any other transmission fluid, especially affordable and economy options. 

There are also specifically engineered additives in the Triax transmission fluid that protect the gears and syncrons as well as protect against any chance of scuffing from the inside. The transmission fluid acts as a buffer and film of protection from any corrosion or eroding. It particularly protects brass and copper components of the transmission because of the special additives. This directly extends the life of your 4r100 transmission!

The transmission fluid also performs optimally regardless of its temperatures, retaining its liquidity at remarkably low temperatures. With a strong seal, you also reduce your chances of leakages and spilling. 


  • Manufacturer: TRIAX Lubricants LLC
  • Weight: 38 pounds
  • Dimensions: 12.56 x 12.56 x 15 inches
  • Model: TRXATFMP


  • Anti-slippage
  • Anti-corrosion
  • Anti-foaming
  • Strong seal


  • Not as affordable as other options
  • Not colored for leak detection

Drivers who use Triax are usually loyal fans of the transmission fluid and have been using it for years and have no plans of trying out other brands. It is one of the more well-known brands out there and while it is more of a premium product, you get such a long list of features that it makes it completely worth it. As long as you’re sure you’ve selected the right variant that is compatible with the 4r100, you are good to go with the Triax Synthetic automatic transmission fluid. 

Buying Guide: Which Transmission Fluid Should I Buy? 

After reading through the transmission fluid options that we’ve listed out: you might be having a tough time deciding which one to go for since they all sound so great. All of the transmission fluids we’ve mentioned are indeed high performing and good for your 4r100 but they all have one feature that shines above the others. You should choose the transmission fluid according to which feature suits your needs the best. 


If you’re big on affordability right now, we don’t blame you. There are so many costs with maintaining a vehicle optimally, and you may not want to splurge on transmission fluid so that you can spend more on something else. Maybe you’re saving up for a rainy day when you have to replace a wonky part. 

Whatever the reason, being big on affordability when searching for the right transmission fluid is perfectly valid. We’d recommend the Genuine Mazda Mercon V ATF as your transmission fluid of choice since it is really affordable, without compromising on performance and quality. 


Not all of us are having trouble with our transmissions. If you’re already enjoying super smooth shifting gears and no other issues, you want a transmission fluid that will simply extend the life of your 4r100 and keep it going like it is right now. This is especially important for someone who is using a second-hand or third-hand 4r100 — even though it’s working fine right now, you’re always concerned about that looming date when it might suddenly die on you (hopefully not mid-ride). 

There are certain transmission fluids that, above all, extend the life of your transmission by keeping it optimally performing for a long time. Instead of focusing on periphery features, it does the sole job of great lubrication and inner component protection, essentially adding a few years to the life of your transmission. The Valvoline Mercon V Transmission Fluid is one such ATF. If you’re big on durability and don’t care too much about other features, you can blindly choose the Valvoline Mercon V to be rest assured that the lifespan of your transmission is taken care of. 


Most Ford truck owners fall into this category — they care about the reliability of their transmission fluid. In fact, going on many Ford forums and asking which transmission fluid to use will result in many warnings about not to use any transmission fluid other than the Genuine Ford recommended transmission fluid. While it is not dangerous to use other brands of transmission fluid as long as you’ve ensured it’s the correct type for the 4r100, you can’t argue that it isn’t safer to use the Genuine Ford transmission fluid. 

Using the Ford transmission fluid is slightly more expensive, especially when you do budgeting for the entire year and factor in how often you’ll have to use it. But there’s no price on peace of mind! You can rest easy knowing that if any issue crops up with your transmission, you haven’t voided your warranty by using the wrong transmission fluid. You can always take it for servicing. 


Maybe you want the best bang for your buck. When you’re spending money on transmission fluid, you want to be able to get the maximum amount of features possible. You want the anti-corrosion, the anti-freeze, the best viscosity in all temperatures, the anti-foaming, the anti-slippage — and all these features and more are in the premium Triax Synthetic AFT

It’s difficult to believe that one transmission fluid can accomplish so much, but that’s why it’s the transmission fluid of choice in mega service centers — it can really do everything. The only possible caveat that we can think of is that you’ll need to perform a thorough flush before using it and also that you need to ensure you’re using the right variant. 

As with a couple of other transmission fluids on our list, there can be some ambiguity surrounding the type of transmission fluid. Always read the labels carefully and check to see if your car (with the exact year, make, and model) is on the list of compatible vehicles with the transmission fluid. 

Questions about Transmission Fluid for the 4r100

Here are some frequently asked questions by people trying to look for the right transmission fluid when they’re using a 4r100 transmission!

What Transmission Fluid does a 4r100 take? 

There is a bit of confusion surrounding which transmission fluid is supposed to be used with the 4r100. This is because Ford actually announced that Mercon was not safe to use with Ford trucks a couple of years ago. However, Ford soon announced that Mercon V is completely acceptable and works great for the 4r100.

The reason why some people have a hangup surrounding it is because it was initially not recommended and now it is. However, there are many people who have been using Mercon V with their 4r100 and see great results. Regardless of brands, Mercon V gets rid of shudders and slippage and greatly increases the lifespan of your transmission. That’s why we’ve recommended Mercon V in all the products in our list. Please note that Mercon LV and Mercon V are not interchangeable and have very different viscosity. Using Mercon LV even accidentally can damage your 4r100 automatic transmission. 

You should also be careful not to simply use any automatic transmission fluid that you can get your hands on. This is not specific to the 4r100 and can cause damage. 

How Long will a 4r100 last? 

The consensus surrounding the life of the 4r100 seems to be that it will last about 120,000 miles. After about 120,000 miles you can start having issues with your 4r100 transmission. However, you will generally come across people who boast of having a perfectly functioning 4r100 and running strong on 175,000 miles. These people will generally credit their transmission fluid with the extra mileage! 

It’s definitely not impossible to use your transmission for 175k but you shouldn’t count on it. Being prepared to get 120,000 miles at the minimum out of your brand new 4r100 is a realistic estimation. 

How much transmission fluid does a 4r100 take? 

The 4r100 can hold a total of 18 quarts of transmission fluid. Keep in mind that you will have to use more when you’re getting the transmission flushed, so it would be ideal to purchase about 20 quarts of fluid for a full flush and fill. 

However, it’s always a good idea to buy more and store it with you since it will encourage you to refill the transmission on a timely basis. There are lots of attractive offers for the 5-gallon or 12-pack variety we’ve listed in this article!

How do I know if I have a 4r100 or a 4r70w? 

Sometimes you don’t know which transmission is loaded onto your vehicle. Before you go about purchasing a transmission fluid it’s very important to know which transmission you have! You can go about this easily: 

  • Check the vehicle certification label. You will find this at the bottom of the driver’s door. 
  • Locate the ‘TR’ sign. This will usually be underneath the barcode on the label. 
  • If it says ‘E’ you have the 4r100 (earlier called the E40D)
  • If it says ‘U’ you have the 4r70w. 

If for some reason you do not have access to the vehicle certification label and want to identify the transmission by looking at it, you can do this as well. 

  • The 4r100 is a big box and has a grid pattern all over it
  • The 4r70w is clearly much more rounded without the grid pattern. 

Frequently Asked Questions

What is the best transmission fluid for 7.3 Powerstroke?

For a 7.3 Powerstroke, it’s recommended to use the SAE 75W-140 gear/transmission fluid, which meets the WSL-M2C192-A specification. It’s best to consult the owner’s manual or your vehicle’s manufacturer for the specific brand and type of transmission fluid for your engine.

How much transmission fluid does a 7.3 4R100 hold?

A 7.3 4R100 transmission typically holds 5.81 QTS of fluid, depending on the specific model and configuration.


Needless to say, the transmission is one of the most important components of your vehicle. It’s important to take care of it by using the transmission fluid, to have a better driving experience and to save yourself the trouble and extra costs of a malfunctioning transmission. We hope that you’ve been able to identify the right transmission fluid for your 4r100. When in doubt, opt for the Genuine Ford Automatic Transmission and Power Steering Fluid to get guaranteed performance and care for your 4r100 automatic transmission.

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