Do I Really Need a Transmission Flush? Yes, and Here’s Why

Does your car have an automatic transmission? When was the last time you changed the fluid? When was the last time you had the transmission flushed? Chances are that you are scratching your head trying to remember. Or, perhaps you are thinking, “That’s just some mechanics way to make money off you. Transmission fluid gets added, but it doesn’t need to be changed.”

There are many different fluids that run through your car, one of them is automatic transmission fluid. The transmission is what sends power to the wheels so you can drive the car. If you maintain the transmission properly, your vehicle can run trouble-free for decades.

The engine in your car uses motor oil for lubrication and cooling. The transmission in your vehicle uses transmission fluid for the same thing. Maintaining your automatic transmission is fairly simple, just follow the manufacturer’s guidelines.

How do you know if your car needs a transmission flush? 

Many people are under the impression that automatic transmission fluid lasts forever. This is 100 percent false. Your automatic transmission fluid, should be a red, nearly transparent color. When your automatic transmission fluid becomes really dirty, it turns a dark brown or very dark no longer clear red color. When automatic transmission fluid wears out and becomes very dirty, it can no longer protect and lubricate the internal transmission parts. This allows varnish and sludge to form inside the transmission.

What Exactly Does a Transmission Flush Do?

A flush does what the name implies. All the old, dirty fluid is removed from the transmission, including the cooler lines and the torque converter. This will ensure that all metal shavings are removed, and fresh, clean transmission fluid will fill your transmission once more.

This process allows your transmission to run at a lower temperature while providing maximum protection to the internal parts.

This is Why a Flush is Important

While you don’t need to do a flush every time you service your transmission, this is an important maintenance item. When the mechanic flushes the transmission, it removes every piece of grit, dirt, metal, grime, and all the transmission fluid. 

Automatic transmissions contain a maze of passages through which transmission fluid must pass to ensure smooth gear-shifting. Unfortunately, transmission fluid deteriorates over time, turning from its original bright red to gray, brown or even black as dirt and metal particles from wearing gears contaminate it. When this fluid isn’t flushed regularly or thoroughly, it’s unable to build up sufficient hydraulic pressure to properly shift gears.

While most transmissions have filters that can be changed and some fluid that can be drained, the majority of the dirty transmission oil is inside a large tank called the torque converter, which holds about 3-5 quarts of transmission fluid. The torque converter has no drain plug and the only way to remove all of the dirty trans fluid is to flush the system.

The best news about a transmission flush is that you probably only need to do this every 50-60,000 miles. Check your owner’s manual for the recommended mileage for your year and model.

The Benefits of Flushing Your Transmission

In addition to truly cleaning out the entire transmission system, there are many benefits to a transmission flush you may not have considered before. 

  • Improves Engine Efficiency

In the same way, that clean motor oil makes your engine run more smoothly because it is properly lubricated with fresh oil, replacing every ounce of transmission fluid can allow both the motor and transmission to run more efficiently. When filters are clogged with dirt and metal, they may shift erratically. If the engine must work harder to make the transmission shift into gear, it not only costs more in fuel but in engine wear.

  • Prevents Transmission Problems

Perhaps one of the biggest benefits of flushing your transmission is that something as simple as flushing the transmission can prevent problems with the transmission in the future. It might even solve minor issues your transmission is having right now. Filters that become clogged with dirt and debris are not only preventing the transmission from shifting properly, but they can cause the transmission, and sometimes even the motor, to overheat due to overwork combined with a loss of lubrication. Regularly changing the filter and flushing the transmission can greatly reduce your chances of future problems with your transmission. 

  • Save Money on Transmission Repairs

If no one has told you, transmission repairs can be quite expensive. The average transmission rebuild is over $2800!  Keeping the transmission clean, cool, and well-lubricated is less expensive than a rebuild, not to mention the expense of loaner cars, in the future.

  • 4. Prevents Major Inconveniences Later On

In the benefits above, we have talked about how flushing your transmission regularly can prevent future transmission problems and engine overheating. Keep in mind that these problems may take a while and they won’t occur 100 miles after you failed to keep your scheduled appointment to have the transmission flushed. This can catch up with you, however, and usually at the most inconvenient time. When the transmission will only work in first gear or reverse, or if the motor and transmission should overheat to the point that the car will not move, even after it cools down, it will be quite inconvenient, at best, to have the car towed, find a loaner car, and pay to have everything repaired. 

In the End 

To sum this all up in a nutshell, take your mechanic’s advice or flush the transmission on your beloved vehicle to keep it running as smoothly and efficiently as possible according to manufacturer instructions. You can avoid expensive repairs and inconvenient breakdowns by having this simple maintenance performed regularly. 

If you still have questions regarding your vehicle’s transmission, if you aren’t sure whether the transmission is working properly, or when you are ready to perform a flush or fluid change, the helpful staff at Hong Kong Auto Service are always here to help you. We have ASE-certified mechanics who can run the appropriate tests and determine if your vehicle really does have a transmission problem.