Is power steering and transmission fluid the same

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Motor vehicles no longer run on just petrol and engine oil. Gone are those days when you could just use any oil in your engine and transmission. The vehicles have grown technologically so much over the years that they have also become delicate and sensitive in their own means.

They now have their specific automatic transmission fluids (ATF) and steering room fluids, for different brands of cars. For those who are still confused with the so many types of oils, fluids and associated terms here is some useful information.

What are Transmission Fluid and Power Steering Fluids?

Though these fluids are quite different from one another, they do have their similarities. They are both hydraulic fluids that cycle through high-pressure pumps that run some high force mechanism.

The fluids are designed to have low viscosity and viscous friction. This means that they can easily withstand as much as 1000 PSI of pressure without heating up much while at work.

They can also withstand reasonably high temperatures and easily flows through thin tubes. They do all this while still supplying the necessary lubricity to protect the rotating pump and sliding mechanical parts from wear and tear.

Some power steering fluids need Dexron like Dexron power steering fluid, or other similar types of ATFs, while other car manufacturers are specific about using fluids that are specialized for the steering wheel but has slightly different properties.

Both fluids, however, have similar seal materials that resist the breakdown of hydraulic fluids. It is always better to follow your manufacturer’s instructions about using the various fluids in your car. Sometimes if you can’t find a specific fluid, the auto parts store usually has a compatible power steering fluid substitute.

Automatic Transmission Fluids

Automatic transmission fluids are necessary for various reasons like lubricating, cooling and preventing rust in the transmission. Not using any ATF, or using the wrong one for your vehicle, can lead to the transmission overheating and producing debris. This leads to the gradual but eventual wearing down of the transmission parts.

Manual transmissions do not require any specific fluids like synthetic oils and ATF. And unlike in manual transmissions, automatic transmission fluids tend to break down under normal use because of the high operating temperatures. This indicates it’s time that the fluid is changed.

As you won’t be changing transmission fluids as often as you change motor oils, it is always better to use the best fluids which effectively increase lubrication and reduce heat.

As assumed, power steering fluid is necessary for cleaning, lubricating and conditioning the power steering system seals. They also transmit the required hydraulic force while steering.

With so many features in them, it’s no wonder that there are so many types of steering fluids in the market in varied formulas.  There however is no guide depicting the perfect fluids to use in your vehicle except for your manufacturer’s recommendations.

You however need to know which PS fluid is right for your car so that you can replace it if there is a leakage. Leakages are the most common power steering problem that leads to the seals hardening and debris wearing away the seal surfaces with time.

Dirty power steering fluids without the right additives only make things worse. The best way to prevent this entire unnecessary headache is by periodically checking, and replacing the right PS fluid.

Buying guide for Transmission Fluids

Transmission fluids are important for your car because they help cool and lubricate the different tranny parts. It also accumulates the dirt and other metal shavings flowing through the car’s system or sitting at the bottom of the pan.

It is better to always perform a transmission fluid flush that gets rid of all the debris in the transmission before pouring fresh, new fluid into the car. Make sure you check its level at least once a month using a dipstick so that you change it on time and avoid any transmission related problems.

You can also tell it is time to change by looking at the transmission fluid colour. The fluid is good if it’s bright red in colour with a sweet smell while a dirty and dark fluid emitting a burnt smell means it’s time for a replacement.

What is the difference between Mercon and Mercon V?

It’s not easy selecting the proper automatic transmission fluid for your vehicle because the wrong one can cause problems. Besides, if your vehicle is under warranty, using a fluid that isn’t approved by its manufacturer leads to voiding the transmission warranty.

While automobile companies develop specified transmission fluids for their vehicles, they don’t make them. It’s the petroleum companies who do that. These companies produce transmission fluids based on the formulas licensed by the company.

These formulas comprise of base oils and additives and the license fee lets the oil company use the automaker’s proprietary ATF brand name. Common names here are Dexron, Mercon, and ATF+4 which are the brand names of General Motors, Ford and Chrysler fluids respectively.

Most of the time, car companies stop licensing old ATF formulas once a new ATF formula enters the market. And the last years have to lead to major automakers introducing many fully synthetic ATFs that are better than their conventional ATFs.

The vehicles that used to run on the old ATF formulas usually also run in the new ATF. The oil company anyway states that the old ATF can be replaced by its new counterpart.

Multi-Vehicle ATFs

Most of the time oil companies try to streamline. Instead of using the car manufacturer’s previous set formula, they try to make a new fluid that meets various manufacturers’ original specifications. They thus end up producing ‘multi-vehicle’ ATFs like fluids that meet the specifications of both Dexron III and Mercon V.

Customers thus find it difficult to find out if a particular multi-vehicle ATF is suitable for a specific vehicle because these multi-vehicle ATFs are manufactured to suit the standards set by the petroleum company. The ATFs quality and applications are generally based on their own testing and not by tests conducted by the vehicle manufacturer.

This has lead to many car makers adopting Dexron and Mercon formulations as their specified automatic transmission fluid like Motocraft Mercon ATF power steering fluid. Besides, as Dexron and Mercon are similar they are considered to be interchangeable.

This has also led to many oil companies claiming that their Dexron/Mercon ATF can be used in various vehicles besides General Motors and Ford. They make these claims just because one model of that company used Dexron/Mercon.

However if you add these fluids to cars that are supposed to run only on ATFs like Mobil 1Dexron VI or Mercon lv then you end up voiding the transmission’s warranty. Always be careful, and avoid using multi-vehicle ATFs advertised to be suitably used in various vehicles.

They are usually just Mercon or Dexron III versions. So unless your car was originally delivered with Dexron III or an earlier version of it or Mercon or Mercon V fluid like Castrol Mercon V, it is better to check the multi-vehicle ATF’s product data sheet before using it. Never take the risk of using a multi-vehicle fluid in your car if you doubt that Dexron III or Mercon ATF is suitable for your car.

The best way to choose the right ATF for your car is through the owner’s manual which states the recommended ATF when the car was new. Here is more about Dexron and Mercon transmission fluids that were in the market but have been superseded now.

Dexron Automatic Transmission Fluids

Dexron, Dexron II, IID, and Dexron IIE are the original GM Dexron ATFs but are not licensed by the company anymore. They have been superseded by Dexron III which in turn is superseded by Dexron VI.

The difference between Dexron II and IIE was its oxidation inhibitors.

Dexron IV transmission fluid is an upgraded version of Dexron III that was briefly used by GM.

Dexron III/Saturn was a version developed solely for some Saturn models.

Dexron VI is the latest GM ATF developed in 2006 for the latest six-speed automatic cars. It is a synthetic blend with tighter internal tolerances and higher shear strength than fluids like Mobil 1 ATF Dexron 3.

It is backward compatible which means that it can be used in any vehicle that first used earlier Dexron versions, and can be mixed with them. However, GM does not advise using fluids like Amsoil Dexron VI in non-GM make vehicles that used Dexron III ATF power steering fluid.

While it’s the specified ATF for some non-GM models with GM transmissions like BMW, it’s not specified for use in GM-brand vehicles with non-GM transmissions or cars imported in the United States.

Mercon Automatic Transmission Fluid

Mercon was introduced in 1987 by Ford and like Dexron II, had its license ceased in 2007. This was done because Ford started recommending using Mercon V for all transmissions that previously used Mercon.

Mercon V is the most common Ford ATF but shouldn’t be used in transmissions requiring Ford Type F. It differs from the original Mercon by containing an additive that is not compatible with some older seals.

It also contains additional friction modifiers that make it more slippery than Mercon. This makes it ideal for trannies designed for it but not so good for trannies that aren’t.

Mercon lv is the latest ATF from Ford that’s factory filled in 2008 and later Ford cars. It is a fully synthetic ATF. As it is not compatible with the earlier Mercon fluids, it cannot be mixed with Mercon or Valvoline Mercon V if replacing them.

In fact, it’s not compatible with other fluids too. Mercon SP is a Mercon V variant with additional additives while the Mercon CVT is meant for models with continuously variable transmissions.

Can you use Transmission Fluid in a Power Steering Pump?

Most of the vehicle manufacturers design their steering systems to run under specialized PS fluids to give best results. There are also some systems that even use automatic transmission fluids for their power steering.

They usually have the words ‘Use automatic transmission fluid’ or ‘Use Dexron’ or ‘Use Mercon’ inscribed on the fill cap or in the owner’s manual.  ATFs offer the advantage of having detergents in them which help keep your system clean.

It is safe and okay to use automatic transmission fluid on the systems that are designed to run on them. However it should not be used on systems that specifically require power steering fluid.

Besides, the recommended power steering fluids are not so expensive and are as easily available as tranny fluids. So you do not end up saving money by using an ATF in your power steering system.

The only instance it may be okay to use transmission fluids in a steering pump is during an emergency. And if done, the steering pump may work only for a short time.

It may soon lead to problems in the steering parts. The only models that permit using transmission fluids in the steering pump are Chrysler, Ford, and GM vehicles.

Exceptional case of using ATFs in Honda Power Steering System

You should however never use automatic transmission fluids in a Honda power steering system. This is because Honda is rather particular about the fluids used in their vehicles. While it’s okay to use an ATF in an older Ford or domestic vehicle, it’s a huge no-no in Hondas and Acuras, especially in J-series engines.

Using ATF in these systems can lead to the abrupt failure of the power steering system. The fluid has a low tolerance level and tends to quickly break down, in less than 40,000 miles. So instead of going through all these problems, it’s better to just use the right fluid.

What happens if the wrong Transmission Fluid is used?

There are lots of problems that may happen like the transmission slipping, not properly engaging gear, rough shifting or not working at all. There is usually progressive damage done to the tranny where while it seems fine at first, it later starts to either slip or shift poorly. In some cases, the transmission may entirely fail too.

If you are lucky, just changing and using the right ATF is all that’s needed to rectify things. However, if you aren’t lucky, then the tranny may get so damaged that it needs a complete rebuilding or replacement.

In the case of manual transmissions, the wrong fluid can lead to the synchronizer rings in them that match internal gear speeds while moving into gear to work less effectively. This, in turn, leads to the shifter feeling stiff or the shifter not falling into gear.

Sometimes the shifter may even grind while trying to put it in. In other words, the wrong fluid can with time wear out the synchronizer rings to lead to premature failure and an expensive transmission rebuild.

So using the wrong fluid in both manual and automatic transmissions can quickly wear out the bearings and gears while producing strange noises and failure.

Even putting the wrong fluid in a CVT transmission may lead to it working well for a while because of the remainder CVT fluid in it. However this is only for a while and it may suddenly stop working, to never work again.

Instead of going through all these problems and headache, it is always better to use the right and best fluid for your tranny because when you compare the costs of a fluid and the tranny, any fluid is naturally a cheaper and better option.

Mixing Transmission Fluids

The most common problems that may occur if you mix transmission fluids is slippage or excessive clutch lockup. This applies to manual and automatic transmissions. In the case of CVT transmissions, things may get catastrophic if another fluid is used in it.

It is generally not advised to mix transmission fluids in older transmissions but may be ok in small amounts when inevitable. The biggest problem that may occur in the case of older fluids is line pressure because changed fluids affect viscosity which in turn affects how quickly pressure is used.

While old Valvoline type FA is generally harder shifting fluid, Dexron III is a lighter option. Dexron VI synthetic transmission fluid can lead to the failure of line pressure in older transmissions. Old transmission clutches generally engage at fixed line pressure.

In case the pressure is low because of viscosity, it leads to the clutches burning up. However, in case of too high pressures, the pistons may slam too hard and cause damage.

There are however some exceptions in fluids that can be used instead of non-recommended fluids, which are the common fluids, like Dexron and Mercon. So while Valvoline Max Life synthetic Trans fluid can be used instead of type F Dexron or Mercon in some transmissions.

The right Transmission Fluids

There may not be that many particular transmission fluids for a manual transmission but in case of automatic transmission, it all depends on what you use, the Trans you have and what fluid it requires.

So while VW and Audi have their own transmission fluids in varying numbers, most of them are ZF HP 19 Trans and are Dexron Mercon 3 with added friction modifiers. This means you will be fine if you add Dexron Mercon in a ZF transmission at first, and then add the right fluid.

However, there are some fluids that are entirely different and incompatible with other fluids, which you will want to remove immediately. The reason for their incompatibility is because different companies use different adhesives in their fluids to bind frictional material to the clutch disks in the transmission’s drums.

Is it okay to mix power steering fluid with transmission fluid?

It is not advised to do so because it may lead to the compromising of your transmission seals because transmission fluids have a different formula. There is however some models that may work when mixed, especially if the fluids are about the same viscosity.

Differences between Power Steering Fluid and Automatic Transmission Fluid

The main difference between the two is that ATF contains friction modifiers and detergents. It’s the detergents in the ATF that helps keep all the contaminants away from the transmission. This is very important as it helps prevent any damage to the hydraulic valves, an important part of the tranny.

The friction modifiers in the automatic transmission help control the heat that builds up while the valves and pump operate in the hydraulic systems. However, both contain the same seal materials that resist hydraulic fluid breakdown.

This is why automatic transmission fluids are known for working in high-temperature ranges. It’s due to their additives which may end up blocking the power steering system’s actuator and a fluid pump.

Can you mix Dexron 3 with Dexron 6?

There may be situations where you may have to refill your tranny fluid, only to find out that there is still some Dexron 3 remaining in the transmission. This is when you wonder if can you mix Dexron 3 with Dexron 6 because the Dexron 6 container reads that it is okay to use in vehicles recommending Dex III.

You wonder if mixing the fluids will create problems or if it is better to have it flushed by a dealer with a filter change. Well, it is basically okay to mix Dex 6 with Dex3 as long as you filter and replace the drained fluid, and there are no shifting problems.

This is because Dexron 6 is backward compatible with earlier transmission hardware. However, you should note that the earlier fluids are not forward compatible with a transmission designed for Dexron 6.  

Though expensive, Dexron VI synthetic can be used in any proportion with past model vehicles that have an automatic transmission, instead of Dexron 3. This is because it has a much lower viscosity out of the bottle when compared to other ATF or Dexron ATFs.

You worry because Dexron VI is synthetic in nature and can ruin the transmission because of the reaction of the different additives in the two fluids.

This is especially true in Honda/Acura and Toyota trannies because their ATFs are designed to work in the transmissions they were designed for. Adding any brand or general ATF into their transmission can lead to immediate failure of the tranny because of lubricity change and hydraulic properties.

About Valvoline Automatic Transmission Fluids

Valvoline has a range of transmission fluids that meet most vehicles’ manufacturer specifications. An example is the Valvoline MaxLife ATF which is synthetic in nature and uses Group III paraffinic oil as its base.

This Valvoline Mercon lv fluid is suitable for all modern automatic transmission applications except for ATF+4 and CVTs. The fact that it is a synthetic fluid means that it comes with an extended drain interval.  

It is not only compatible with transmission seals; it has an agent as an additive that conditions seals to prevent leaks. Valvoline MaxLife ATF also includes cleaning agents that can clean off deposits from friction-prone parts and even discourages the formation of deposits.

It is compatible with Dexron VI, Mercon V, and Mercon lv and works on most European cars including BMW, Audi, Saab, and Mercedes-Benz.

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About Castrol Automatic Transmission Fluids

Castrol automatic transmission fluids are formulated to restore smooth shifting in vehicles. It can even smoothen the shifting of gears in cars that have run more than 75,000 miles.

Castrol boasts of a wide range of ATFs that are engineered to protect important transmission parts. This includes the products licensed by Ford, GM and Chrysler and fluids meeting the JASO requirements of popular Japanese imports from Nissan, Honda and Toyota.

Most of Castrol Transmax products like the Castrol Transmax Devron VI include Smooth Drive Technology comprising of active control molecules that automatically adjust their friction level even in varied pressures and speeds. This, in turn, provides for a smoother driving experience for a longer period of time.

Besides Castrol ATFs are formulated with extra friction durability and anti-wear chemistry that protects all the transmission parts much better and in the process, protects and prevents extensive transmission damage and repair costs.

This is integral in today’s driving condition which can lead to an uncomfortable ride and damage if the transmission fluid doesn’t protect the transmission moving parts.

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Is it better to use power steering fluid or transmission fluid?

Can you mix power steering fluid and transmission fluid in your power steering pump?

Does Ford use transmission fluid for power steering?

What can I substitute for transmission fluid?