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transmission fluid change

The Best Transmission Fluid 2020

Both manual and automatic transmissions require a service that includes a transmission fluid and gasket replacement. Compared to manual transmissions, an automatic requires much more care and attention with specific ATF (Automatic Transmission Fluid) for smooth gear changes.

The best transmission fluid is the Mobil 1 112980 Synthetic ATF, which promotes excellent lubrication, smooth shifting, cooler operating temperatures and long life.

Some of the first automatic transmissions used motor oil as the lubricant but that is not suitable for todays complex transmissions. This is due to the large amount of heat produced from the extra gears that require specific transmission fluid.

Best Automatic Transmission Fluid

Transmission FluidSynthetic?Specialty
Mobil 1 112980YesAll Rounder
Royal Purple Max ATFYesPerformance
Castrol TRANSMAXNoValue for Money
ACDelco 10-9395NoOlder Vehicles
Castrol 03518NoHigh Mileage

Automatic transmission fluid provides lubrication, cooling, anti-rust and other qualities. Without it, the transmission will overheat and produce debris, which will gradually wear down the components within the transmission. Unlike a manual, the automatic transmission fluid will break down under normal use due to the higher operating temperature and will require changing.

Manual transmissions can use a range of different fluids from ATF, synthetic oil and more (refer to the owners documentation) and doesn’t require as much attention.

Considering that changing your transmission fluid is far less regular than changing the motor oil, it makes sense to use the best there is. Below is a list of the best transmission fluids that increase lubrication and decrease the heat.

Mobil 1 112980 Synthetic Automatic Transmission Fluid

Mobil 1 Synthetic ATF is a premium transmission fluid that has a high velocity index of 176 and excellent remarkable cold temperature flow. Unlike many of the cheaper alternatives, the Mobil 1 will not break down as easily at higher temperatures and will contribute to cooler operation and smoother shifting.

For those that live within a cold climate, the Mobil 1 will provide excellent performance at temperatures as low as -54 degrees Celsius.

Mobil 1 state that this automatic transmission fluid will work with a range of vehicles from Ford, GM and the majority of domestic vehicles. Overall, it is the best transmission fluid that is fully synthetic and promotes cool and smooth operation.

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Royal Purple Max High Performance ATF

The Royal Purple 06320-6PK Max ATF Synthetic Automatic Transmission Fluid has been developed to be high performing and reduce heat by a great margin. This is achieved by a low co-efficient of friction and high film strength.

Royal Purple state that due to the more oxidation stable formula, it will be longer lasting and provide smoother shifting.

Unlike some of the other automatic transmission fluids, the Max ATF can be mixed with other ATF’s, which is great for top ups. However, if you were to perform a proper transmission service, you would want to completely flush the system. Overall, it is the best high performance transmission fluid and recommended for the majority of passenger vehicles.

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Castrol is another huge brand worldwide with a range of servicing parts and fluids for the automotive industry. The Transmax ATF meets both MERCON and DEXRON-III H requirements and satisfies requirements of DEXRON, DEXRON-III, IIE and II.

The Castrol Transmax promotes enhanced friction durability for smooth gear changes and can even be used in some power steering applications where MERCON is a requirement.

Overall, it is a top rated automatic transmission fluid that can be used in a range of vehicles and even for your power steering. Overall, it is the best transmission fluid for the money as it offers good value per gallon compared with the alternatives.

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ACDelco 10-9395 Dexron VI ATF

The ACDelco automatic transmission fluid is backwards compatible with the previous DEXRON ATF and can be used as a replacement fluid for older vehicles/transmissions. This is due to the later DEXRON consisting of enhanced friction durability, foam control, oxidation resistance and more.

This transmission fluid is fully approved and licensed by GM and recommended for all GM models from 2006 and newer.

Overall, it is ideal for older vehicles and offers relatively good value for money but not as cheap as the Castrol alternative. However, that being said it is by far one of the most popular automatic transmission fluids in the US and offers a range of benefits that others cannot compete with.

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Castrol High Mileage Transmission Fluid

As your vehicle ages and the transmission clocks up thousands of miles, its important that the fluid you use reflects its condition. The Castrol 03518 Transmax ATF is suited for high mileage vehicles where the transmission has covered over 75,000 miles.

This ATF has been designed to reduce leaks and promote smooth shifts, which a tired transmission can suffer from. Therefore, the fluid itself contains additional seal conditioners, extra cleaning agents and greater frictional durability qualities.

Overall, it is the best transmission fluid for high mileage vehicles and Meets General Motors DEXRON-IIIH Requirements and Ford MERCON Requirements.

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Transmission Fluid Buying Guide

Transmission fluid plays a vital role in the cooling and lubrication of a vehicle’s parts as it circulates through its components. In the process, it accumulates dirt and other metal shavings over time, sometimes sitting at the bottom of the pan and in some cases flowing through the car’s system.

It is for this reason that most auto dealers undertake a transmission fluid flush to ensure the debris is removed before pouring of new transmission fluid into the car.

By regularly changing the transmission fluid, you can evade transmission problems and thus it is essential to check its condition and level once a month using a dipstick. You can even use a transmission additive to help maintain performance and protection over the years too.

A sweet smell and a bright red color is an indication of good transmission fluid, whereas a dirty, dark and with a burnt smell is a sign it needs replacement. Moreover, if the transmission fluid is at low levels, add some more and ensure there are no leaks.

How Often Should You Change Transmission Fluid

The period transmission fluid needs changing varies from one car model to another. Therefore, knowing your car manufacturer’s recommendation on how often to service the vehicle is vital.

While other cars and trucks have varying range when the transmission fluid should be changed, it mostly ranges from 30,000 miles to more than 100,000 miles.

However, newer version cars have transmission fluid meant to last the entire lifetime of the vehicle.

Moreover, tougher conditions in which one is driving may affect the frequency one needs to change the transmission fluid. It includes prolonged high-speed driving, driving in cold weather and also trailer towing.

fluid for transmission

How to Change Transmission Fluid

The process of changing the transmission fluid is one messy job since many pans do not have drain plugs and the entire pan must be detached. After that, the filters can be changed even for cars not having drain plugs.

Therefore, the general process is hectic and needs a lot of patience especially true if one is teaching themselves to do it since it will be cheaper in the long-run. Some of the tools necessary to carry out this activity include a new transmission filter, its O-ring, a torque wrench and a large pan to catch the fluid.

Below are some of the steps one should follow while changing the transmission fluid.

Put Your Vehicle on Ramps

Slowly put your car on ramps or using jack stands, jacking it up from the front part of the vehicle. Ensure, you block the wheels and at the bottom place newspapers on the floor to prevent the oil spills from getting onto the driveway creating a whole mess.

Upon completion, get rid of everything but do not dump the oil in the yard or trash can, instead, seek the advice of an auto part dealer on ways to correctly dispose the oil or where to dispose the oil.

Locate the Transmission Pan

Using the owner’s manual as a guiding point, find the transmission pan and directly below it, place the oil pan you’ll use. Follow that up by removing the bolts at the same time keeping your face away.

Now that the seal is broken on the bolts, the fluid will slowly start to drip out, and patiently wait until the oil completely drains into the drain pan. The deposits and sediments should be washed out of the pan using fluid and not water while inspecting the container for any debris.

transmission gasket

By doing so, one can determine whether or not the transmission is running as it should be or trouble is in the looming soon. Nevertheless, not everyone can detect this thus the need for trained personnel to do so, with the first change with little or no debris, but successive changed should be completely clean.

If waste is present and the car’s age is relatively new, this is a warning sign. Furthermore, gearboxes are so delicate such that any accumulation of dirt and dust even in the lowest levels signals a problem is emerging.

Checking the Gasket

Carefully look if the gasket needs replacing if so, switch for a new one. If it is not worn out, clean the transmission housing and the pan. However, to save you time repairing it in future, it would be advisable to replace the gasket.

Finally, a thin layer of RTV sealant should be applied to the pan’s flange thereby assuring a leak-proof seal that is nice and tight.

Remove the Filter

After completely draining off the fluid, remove the filter cautiously since the filter to has fluid in it too. Go on and replace it with your new filter, tightening it according to the guidance of your owners’ manual.

Follow this up by constricting the bolts firmly and after this is done, add the recommended amount of fresh fluid cautiously with the help of a funnel to ensure there’s no spilling.

fluid change on transmission

Test the Vehicle

Start up the car and let it warm up for a while, a few minutes later shut off the vehicle, checking if there are any leaks. If no leaks are present, run the car on a ground level and at operating temperature shifting through all the gears testing if they work as expected. After that, park the vehicle and when the engine cools down, check with a dipstick the oil level and color are as recommended.

How Hard is it to Change the Transmission Fluid

Whereas the process can be complicated, hectic and untidy for the average person, it requires a great deal of patience and expertise to undertake it. It is especially true unlike changing engine oil which most people are conversant. Nonetheless, with continued practice, this is something one can carry out for themselves, with the first time need of guidance critical.

Despite this, most modern cars have put in place transmission mechanisms that need the dealer’s service computer to gauge temperature levels and other parameters. It, therefore, makes it impossible for the average guy to be able to work on it.

If you have access to a vacuum oil extractor, this can make your job a lot easier. Rather than having to unbolt filters, gaskets and so forth, you can simply vacuum all the old oil. Once all the old oil has been removed, you can add the transmission fluid. However, depending upon how long it has been since the last change, you may want to replace the filter and gasket.

About The Author

procarreviews author

Dan is an automotive journalist and owner of over 10 cars ranging from supercars, luxury modern cars, classics and your good old beater cars. He always like to get his hands dirty with nut and bolt restorations and detailing sessions with the latest products. Feel free to read more about our team.

What Are Your Thoughts?

  1. Dear Dan,
    I feel lucky to have stumbled on your site.
    I drive a 1983 Toyota Supra that needs some ATF.
    Some online sources claim that if I put in the wrong ATF,
    I’ll lunch my transmission. My owner’s manual says “Type F (Ford)”
    but the manual was written before many changes
    in ATF technology. Toyota sent me a list but no definite answer.
    So here I am hoping for a definite “Use XYZ ATF.”

    Grateful in advance,
    Burt Wetanson

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