Toyota truck transmission service

Servicing your automatic transmission is the most important thing you can do to extend the life of your transmission. Frequently Boise drivers don’t service transmissions because they don’t think about it until their transmission has a problem. 

Before we answer the question of why you should service your cars automatic transmission lets talk about customer concerns regarding automotive maintenance.

Many auto owners believe repair shops are just selling them transmission services to make money. That may be true but if we step back and look at the bigger picture we can see that there are many reasons why shops recommend services. Some are honest recommendations that are from mechanics looking out for their customers. Sometimes a recommendation to service your transmission is not based on accurate information.

When shops recommend servicing a transmission they are doing it for any number of reasons:

  1. A vehicle has a mileage that is at or beyond the manufacture recommended service interval. Since mechanics know it’s an important service to protect a transmission, they recommend the service. The bad thing about this recommendation is that the mechanic may not know the maintenance history of the vehicle. It could have recently had the service done. If so, having the service again it an unnecessary expense. 
  2. A mechanic looks at the fluid color and determines it should have a fluid change. This method of analysis is subject to several conditions that may or may not indicate its due to be changed. Conditions like:
    • The mechanic may not be skilled enough to know if the fluid needs replacement
    • The color and appearance method is not precise because the fluid could have been recently changed but the old fluid has mixed with new fluid so doesn’t look new

There are several things auto owners can do to protect themselves from unnecessary shop recommendations:

  • Keep good records of when services are performed
  • Know the mileage and time intervals that services are due 
  • Have one shop that performs services so they have all your cars records

Now lets answer the question that is the main focus of this article.

Why service your automatic transmission?

Transmission fluid has many tasks. One is to lubricate the internal rotating parts in the transmission. Another is to perform hydraulic fluid functions by creating pressure to apply clutches and bands. A third is to cool the transmission. 

It’s important to keep the transmission fluid clean and in good condition so it can do these jobs. Clean fluid lets the internal valves move freely and allows the solenoids to pass fluid without restriction. Clean fluid also lubricates well, which reduces heat. 

One of the most important reasons to service your transmission is to have the filter changed. If a filter inside the transmission isn’t changed it can get plugged and reduce internal pressure so much it can destroy the transmission. At Wayne’s Transmissions when a transmissions filter is changeable, we always change it during a service.

Here’s a quick note about transmission flushing vs. draining and filling, with a filter change. Many auto shops, quick lubes and dealership service departments sell flushing. These flushes do remove all the old fluid but they ignore the filter replacement. We discuss this in more detail later in the article.

Your car maintenance recommendations are listed in the owner manual. Wayne’s recommendation is more frequent than that of the factory. We want to keep that filter clean and flowing properly so the pump can produce the fluid pressures the transmission needs. We recommend filter changes on most vehicles around 20,000 to 30,000 miles. 

Many newer vehicles have sealed transmissions, which means you can’t change their filter. On those vehicles we recommend changing the fluid every 10 to 12,000 so they don’t get dirty. Keeping transmission fluid clean will extend your transmissions life. Most transmission failures are due to low fluid from leaks, heat from heavy use or hot summer days that breaks down the fluid. Regular maintenance services can reduce these failures significantly.

Another good reason to change or service your transmission is that we can keep an eye out for leaks. A small leak can cause fluid to go low which can damage or destroy your transmission. Don’t let a minor problem like a leak turn into something major like a transmission rebuild or replacement.

car transmission filter replacement

Two final points to mention about automatic transmission services

Many of today’s transmission have strict requirements for the type of fluid they use. Putting in the wrong fluid or mixing fluids can cause transmission failure. More importantly if your car is still under warranty, it can void the warranty. For this reason it’s critical to go to a shop where the mechanics know for sure what type of fluid to add.

Another point to mention is that many transmission repair shops don’t recommend flushing automatic transmissions with machines. They recommend drain and fill services with filter replacement. Using a machine can loosen metal particles and carbon fibers stuck in harmless places in the transmission. These particles can move into small orifices and plug solenoids. For this reason Wayne’s Transmissions, and most transmission shops, don’t machine flush transmissions.


We’ve described why you should service your automatic transmission. We discussed concerns about not trusting auto shop recommendations. And we shared what to know about transmission services so you can protect yourself from dishonest or non-skilled auto mechanics.

There are many honest shops and mechanics that are looking out for you and your car when they recommend maintenance services. If they are transmission professionals like us Wayne’s Transmissions they will take good care of you and your car.

Transmissions pass engine power to your wheels. To function properly and efficiently your transmissions fluid must lubricate and cool your transmission. Keeping fluid clean and full will extend the life of your transmission and save you money on auto repair expenses.

If you’re interested in a service for your automatic transmission give us a call at Wayne’s Transmissions or make an appointment online.

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