Experts weigh in on when to replace your transmission fluid and why it’s essential for your vehicle’s longevity

Dear Mike,

I recently purchased a used car and have heard conflicting advice about when to replace the transmission fluid. Some say every 30,000 miles while others claim it can go up to 100,000 miles. I want to ensure the longevity of my vehicle, but don’t want to waste money on unnecessary maintenance. Is it really necessary to replace my transmission fluid or can it wait until later?


Dear Cassiopeia,

Congratulations on your new(er) car! It’s always exciting to get behind the wheel of a new ride, whether it’s brand new or just new to you. As for your question about transmission fluid, I’m happy to say that the answer is not as conflicting as you may have heard.

First off, let me say that it is absolutely necessary to have your transmission fluid replaced at regular intervals in order to ensure the longevity of your vehicle. However, the frequency of those intervals can vary depending on the make and model of your car, as well as the type of driving you typically do.

As you mentioned, some folks say that transmission fluid should be replaced every 30,000 miles, while others claim that it can go up to 100,000 miles. The truth lies somewhere in the middle.

Most manufacturers recommend having your transmission fluid replaced between 60,000 and 80,000 kilometers. This interval should be followed unless you do a lot of heavy towing or hauling, frequently drive in stop-and-go traffic, or drive in extreme temperatures. In those cases, it’s recommended to have the transmission fluid replaced at shorter intervals.

It’s important to keep in mind that not all transmission fluid is created equal. Many manufacturers have specific transmission fluid requirements in order for their vehicles to operate properly and remain trouble-free for years to come. These fluids often include additives like friction modifiers and detergents, which are designed specifically for modern, computer-controlled automatic transmissions. Not following the manufacturer’s specifications and using the wrong fluid can cause serious damage to your transmission.

Now, onto the question of pricing. You mentioned that not all pricing is the same from dealers and service providers, and that can certainly cause confusion. In most cases, a “transmission service” involves draining about 3-4 litres of fluid from the transmission and adding fresh fluid to the transaxle. This can be completed at most quick lube shops, but it may not be the complete solution.

The more expensive and arguably proper way to complete the service is through a complete “transmission fluid exchange service.” This involves hooking up a fluid exchange machine in line with the transmission’s oil cooler assembly, which allows for the full evacuation and replacement of all of the transmission fluid within the unit. This method is more expensive, but it’s also more effective since it replaces all of the transmission fluid instead of just a portion of it.

If your vehicle has over 150,000 kilometers and has a serviceable transmission filter assembly, it’s always recommended to replace the filter as well. This usually involves the removal of the transmission’s oil pan assembly, which is an additional charge. Your service provider should be able to advise you on whether your vehicle has one of these serviceable filters or not.

In short, it’s essential to have your transmission fluid replaced at regular intervals in order to ensure the longevity of your vehicle. Follow the manufacturer’s recommendations and use the proper fluid for your make and model. And, if you’re ever in doubt, don’t hesitate to ask your service advisor for more information. Remember, taking care of your car can save you money in the long run by preventing costly repairs down the road.

Thanks for writing in, Cassiopeia. Happy driving!


Mike Urban