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Does Changing Transmission Fluid Help Shifting?

Modern automatic transmission system. Featured image for "Does Changing Transmission Fluid Help Shifting?" blog post.

Whether you are a heavy equipment operator,  in the automotive industry, or running a fleet of cars, you may be experiencing transmission problems, such as shifting issues, in some of your equipment.

When you drive your truck, bus, or car, do you hear strange noises as your transmission is shifting? Does your equipment need to be sent to the auto repair shop to check the transmission? Will the transmission need to be replaced? Does the torque converter need to be changed? Is it more a case of a dirty transmission that needs a change of the fluid and a change of the transmission filter, or is it simply low fluid levels?

In many cases, the genesis of these problems most likely lies in the type and quality of the lubricant being utilized.

The obvious question then is: Does changing transmission fluid help shifting?

Let’s discuss how changing your transmission fluid could be a simple solution to this frustrating problem.

Reasons Why Your Transmission Is Acting Up

Automatic transmission gear box.
Rather than asking the question ” Does my transmission need to be repaired?”, the more hopeful question would be: Does changing transmission fluid help shifting?








There are various types of transmission oils that we’ll discuss in this blog post. First, let’s take a look at a multi-vehicle automatic transmission fluid.

The very first building block that is considered when constructing a multi-vehicle ATF fluid would be the choice of base oils. If the goal of the lubricant manufacturer is to provide a cheap bottom tier ATF fluid that basically meets OEM specifications, then the choice would be using standard conventional petroleum oils.

This old fashioned style base oil finds uses in light duty applications. There are a lot of technical and performance limitations if a fleet owner or heavy equipment operator is using such a transmission fluid.

One of the limiting factors of a conventional petroleum base oil is its natural molecular structure. The molecules are uneven and of different sizes. This means the fluid creates a tremendous amount of fluid friction due to the uneven sized molecules.

Over time, this fluid friction generates its own unwanted heat. Couple that with the friction caused by the moving mechanical parts and the temperatures inside the transmission start to climb quickly.

Conventional petroleum base oils are susceptible to heat degradation. As the oil oxidizes when exposed to heat, sludge deposits slowly start to form. This buildup of unwanted contaminants will slowly effect shifting. A fresh fluid quickly becomes an old fluid, which leads to wear and tear. Ultimately, these problems and this downward spiral can lead to transmission failure.

Beyond the molecular structure of a conventional transmission fluid, the base oil naturally contains other unwanted byproducts. Wax is one of the main byproducts that serves no real useful function other than causing the oil to thicken during cold temperatures.

If an oil thickens too much when the temperature drops, then it is extremely difficult for this thick oil to travel throughout the small and tight oil passageways. Between the fluid friction and the wax-induced oil thickening, it is easy to see how problems start to arise when shifting.

Initially, the low cost of such a conventional automatic transmission fluid seems quite attractive, but over a long period of time, there is a more frequent need to change the transmission fluid. Because of frequent trips into the shop, the maintenance schedule starts to be disrupted and parts become worn out too quickly, all because of choosing an initial low price.

It has been found that the cost of parts and downtime is much more expensive than the cost of a quality lubricant, and that cheap oil suddenly becomes quite expensive. So, if you’re asking yourself the question “does changing transmission fluid help shifting?”, remember that while the answer is yes, you must refrain from reaching for the cheapest transmission fluid on the shelf and instead opt for a high performance synthetic transmission fluid.

Why Synthetic Base Oils Improve Shifting

Street cleaning truck.
A synthetic based transmission fluid is ideal for stop and go refuse trucks due to the oil’s ability to withstand these extreme operating conditions.









Let’s take a look at the second choice a chemist at another lubricant company can choose.

Their philosophy is one of maximum performance without consideration to cost. In this case, the chemist has decided in using a synthetic base oil. Why? Well, a synthetic base oil is made up of even, perfectly sized molecules.

Each molecule, being of the same size, provides minimal, if any, fluid friction. This is a radical departure from conventional petroleum base oils.

Additionally, a synthetic base oil is devoid of wax and other harmful byproducts. Also, a synthetic base oil has a high viscosity index number; much higher than a conventional base oil. A high viscosity index number means the oil will maintain and hold its viscosity throughout a very wide temperature range. In other words, if the equipment calls for a transmission fluid that is a 5W20, it will maintain this exact viscosity regardless of whether the temperature becomes very cold or very hot.

Unfortunately, conventional oils of the same viscosity will thicken during cold temperatures and thin out during hot temperatures. This is not the case with a lubricant manufactured using synthetic base oils.

Because of the characteristics of the base oil, a synthetic automatic transmission fluid will protect the shift quality built into the vehicle.

So, when asking the question “does changing transmission fluid help shifting?”, remember that only a high performance synthetic transmission fluid will get the job done. A transmission fluid utilizing synthetic base oils offers compatibility with gaskets, seals, and all the various types of transmission parts. Such high performance base oils provide the best in durability and long service life. This is even before we’ve discussed the additive chemistry that is blended into the base oils.

How To Extend the Life of Your Transmission

School bus.
If the complaint is of inconsistent shifting, then the following question arises: “Does changing transmission fluid help shifting?”








The next phase in constructing a transmission fluid that will maintain a vehicle’s proper shifting patterns would be the type of special additives used. ATF fluids that are made using conventional base oils will typically contain the bare minimum of additives required to meet minimum OEM specifications.

Again, the philosophy in such an approach is more about economics rather than performance… The goal is to create a product just good enough to pass and meet OEM requirements.

Realistically, such oils should not be considered by mechanics for heavy equipment or fleet operations. Unfortunately, these low performing oils do find their way in such commercial applications far too many times. Once the driving starts, the trouble begins. These low quality oils cause slipping and slowly, the damage causes more problems with shifts and very soon the warning signs come more frequently.

In contrast, a specialty lubricant manufacturer will look to far exceed OEM specifications. This type of performance requires a much higher volume of specialized additives. These additives are required to fight foam, oxidation, wear, rust, leakage, and cold weather. The goal is to prevent the most common problems and through offering a superior lubricant, your transmission will be shielded from any lubricant breakdown that could cause damage.

By utilizing robust volumes of the necessary additives, transmissions are provided exceptional protection and the oil is sturdy enough to offer extended drain intervals. In most cases, transmission life is doubled and drain intervals tripled.

The goal is to maintain cleanliness inside the transmission and to provide the required lubrication film to keep parts from wearing away in both cold or extremely hot temperatures. As we’ve stated a weak transmission fluid can cause numerous issues, so the obvious strategy is to choose the highest quality automatic transmission fluid possible. A state-of-the-art ATF fluid needs to be changed infrequently, if at all, and because of its ability to withstand heat, consumption is eliminated and the fluid level remains constant.

A high performance synthetic ATF fluid remains a new fluid throughout its life and the thought of an oil change almost becomes a thing of the past. A synthetic multi-vehicle transmission fluid can deliver in these areas.

Protecting Shift Quality

Yellow dump truck.
Utilizing a transmission fluid that withstands extreme heat will help maintain proper shifting quality.








To maintain and protect the shift times and shift quality, special friction modifiers are required. It is important that the correct and specialized additives are blended into the lubricant so that the oil is durable enough to provide and maintain the quality of the shift.

The transmission fluid must be able to deliver a smooth and acceptable shift to the operator even after many miles have been driven on the fluid, even when the fluid is absolutely new.

For fleets running transit buses, school buses, emergency vehicles, etc., a high performance synthetic ATF fluid should deliver durable anti-shudder performance.

Beyond these performance requirements that are critical for maintaining proper shifting, the fluid should be resistant to cold weather thickening, viscosity shear down, and any other possibilities of shortened oil life.

Since the finest additives and synthetic base oils are used, it can be expected that the fluid will be protected against oxidation and thermal degradation. Translated, this means the fluid will keep your transmission free of damaging varnish and sludge. These two culprits are always at the center of causing shifting problems.

If the automatic transmissions of your fleet have been using conventional low priced automatic transmission fluids, then the time has arrived to change the fluid. When conducting a fluid change, your vehicle most likely needs a transmission flush. Once that has been done, the transmission can be filled with a high performance synthetic ATF fluid, which should alleviate the hard to shift problems you’ve been having.

So, does changing transmission fluid help shifting? If you can eliminate sludge, varnish, viscosity breakdown, cold weather thickening, foaming, and viscosity thinning simply by changing to a better transmission fluid, then the answer is clearly yes!

Choosing A Better Gear Oil Can Solve Shifting Problems

Gear box.
When asking the question “Does changing transmission fluid help shifting?”, the answer is a definite yes, due to the combination of synthetic base oils and heavy duty additives in high performance transmission fluids that eliminate potential problems that can lead to shifting issues.









When considering problems shifting gears in a manual transmission, the choice of lubricant is critical. It comes down to how strong and robust the gear oil is when dealing with heat, cold temperatures, and extreme pressure.

Gear oils also benefit greatly if the correct quality base oil is chosen. There is no need to rehash the severe limitation inherently found in conventional, low cost lubricants, including conventional gear oils. The fact is, only high viscosity index, highly refined base oils that have had all impurities removed should be considered.

By eliminating all unnecessary byproducts and impurities, the chance of sludge, varnish, and other unwanted byproducts forming is slim or none.

If the goal is maximum protection and performance from any heavy piece of equipment, then let’s try to agree that only the finest quality lubricants should be considered. Manual transmissions and final drives will greatly benefit from a high quality specialty gear oil.

Heavy truck gear box.
It is imperative that the transmission fluid withstand heat so that synchronizer coking issues do not appear that can cause problems in shifting.

Does Changing Transmission Fluid Help Shifting? Yes… If It Can Take the Heat!

Red semi truck.
Does changing transmission fluid help shifting? Of course, but additional benefits such as extended drain intervals, longer equipment life, improved fuel economy, and less downtime will also be realized when changing to a high quality fluid.









Many modern transmissions and final drives are now having to perform in operating temperatures ranging from 280 degrees F all the way up to 320 degrees F. These extreme transmission temperatures are causing transmission synchronizer coking.

This symptom will indicate difficulty in gear shifting or changing. Typically, low quality, light duty gear oils simply are not durable enough to withstand such high operating conditions. The conventional oil starts to oxidize, break down, and cause coking issues. It becomes more difficult to drive the vehicle and the transition from the clutch creates an inefficient transfer of power from the engine throughout the drivetrain system.

Simply switching to a heavy duty specialty gear lubricant will eliminate these coking deposits and rid the transmission of these shifting problems.

Also, the higher quality gear lubricant will deliver superior oil flow to bearings and gears due to the elimination of any deposits that may have hindered the oil flowing through the passageways or filters.

Much like our above discussion with the synthetic ATF fluid, avoiding damaging contaminants and deposits will eliminate any shifting problems.

So, to wrap things up, does changing transmission fluid help shifting? Without a doubt, switching to a high performance transmission fluid from a conventional fluid will bring countless benefits. The bottom line is that the cheapest fluid is one that eliminates problems, reduces downtime, improves performance, and saves money in the long run. The only choice to gain these types of results means an investment in the finest possible lubricant. This approach is always the most cost-effective when one compares the cost of expensive parts and labor costs.

Note: Always check your owner’s manual for the proper viscosity and specification.