Skip the auto shop - Our mechanics make house calls

How Often Do I Need to Replace the Transmission Fluid?

transmission fluid service

The basic definition of a transmission is the part of a vehicle that transfers the power from the engine to the wheels. How a transmission works depends on whether or not the vehicle is an automatic or a manual.

Manual vs. automatic transmissions

A manual transmission has a set of gears that are lined up on a shaft. As the gearshift and clutch, located inside the car, are manipulated by the driver, the gears move into place. As the clutch is released, power from the engine is transmitted to the wheels. The amount of power, or torque, is dependent upon the gear that was chosen.

With an automatic transmission, the gears are lined up on the shaft, but the gears change by manipulation of the gas pedal inside the car. As the driver presses on the gas pedal, the gears shift up automatically depending on the current speed. If the pressure on the gas pedal is released, the gears cycle down, again depending on the current speed.

Transmission fluid lubricates the gears and makes it easier for them to move as the process of switching gears is completed.

How often do I need to replace the transmission fluid?

Again, this depends on if the vehicle is automatic or manual. In an automatic transmission, there is higher heat produced, which means that there’s going to be more carbon produced, which will contaminate the transmission fluid. Over time, these contaminants will cause the fluid to thicken and no longer do its job effectively. Manufacturer specifications for automatic transmission fluid vary considerably, from 30,000 miles to never. Even if the user’s manual says that the fluid will last the lifetime of the car, the fluid level should be checked periodically, in case a leak develops.

In a manual transmission, the recommendations can also vary widely, but for different reasons. Most manufacturers suggest 30,000 to 60,000 miles as the point at which you should change the transmission fluid in a manual transmission. However, vehicles with transmissions that are under ‘high stress’ should change the transmission fluid every 15,000 miles. ‘High stress’ for a manual transmission would be situations such as being driven on lots of short trips where gears are changed more often. If you live in a city and rarely put any highway miles on your vehicle, the transmission is under high stress. Other situations include lots of mountain driving, and any period when a new driver is learning how to use a manual transmission.

Signs you should check your transmission

Even if you haven’t reached the mileage threshold indicated by the vehicle’s user’s manual, the transmission should be checked if the following symptoms are noticed:

  • If a grinding sound is heard from underneath the vehicle while the engine is running, but the car is not moving.

  • If you have problems shifting gears.

  • If the vehicle slips out of gear, or if the vehicle doesn’t move when the gas pedal is pushed.

Occasionally, the transmission fluid can become contaminated to such a level that it needs to be flushed before the manufacturer specifies.

No matter the type of transmission, changing the transmission fluid is not a quick process that can be taken care of with a wrench and a nozzle. The vehicle will need to be supported, and the old fluid will need to be drained, and disposed of properly. Furthermore, the transmission fluid filter and gaskets will need to be inspected. This is the type of vehicle maintenance that needs to be left to licensed mechanics rather than attempted at home.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.


Post a question and get free advice from our certified mechanics.


More related articles

Insurance Requirements for Car Registration in Kentucky
The Kentucky Transportation Cabinet requires that all drivers in Kentucky carry liability automotive insurance, or “financial responsibility” in order to operate a vehicle legally and maintain vehicle...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
P0291OBD-II Trouble Code: Cylinder 11 Injector Circuit Low
P0291 code definition When your vehicle’s PCM registers the P0291 code, it means that a voltage reading came from the fuel injector circuit – for cylinder number 11’s fuel injector –...

Related questions

Q: Buying a Mazda 5 with 4 cylinders

My advice is would be to look for another model. That Mazda is now nine years old. If it has an automatic transmission, that makes one of the poorest automatic transmissions in the world and they cost many thousands to...

Q: Transmission isn't shifting properly

It sounds like you have a transmission leak somewhere that is causing the system to get low. The transmission will not shift correctly if the fluid is low or if you put in the incorrect fluid. You should have the...

Q: car will not pass e-check.

N/A usually means the monitor isn't available on your year make and model vehicle. An emissions monitor should pass or fail or show ready and not ready after the drive cycle has been complete. In most cases, all drive cycles...