Checking Transmission Fluid

One of the common questions asked by car owners is how often to check and change the transmission fluid to assure smooth, trouble-free operation of the vehicle. The answer depends on the type of transmission (automatic or manual), the type of vehicle, and the use level of the vehicle (family car vs. heavy hauler).

Here we’ll take a quick look at what transmission fluid does and offer some guidelines on when to replace the fluid.

Transmission Fluid Basics

Automatic transmission fluid is a lubricant that reduces friction between the moving parts of your transmission. In cars with automatic transmissions, the fluid also acts as a coolant and helps transmit energy efficiently from your car’s engine to the transmission. In manual transmission vehicles, lubrication of moving parts is also the main goal, but is achieved using oils of varying weights and viscosities, depending on the manufacturer recommendations for the vehicle and on the demands placed on the transmission (high heat, heavy hauling, etc.).

Automatic

For most automatic transmissions under typical driving demands, it is suggested that the transmission fluid be changed between 60,000 and 100,000 miles. This is done because, over time, transmission fluid begins to degrade in the hot environment of your car’s engine and will lose viscosity (stickiness). Also, over time, debris (in the form of microparticles from your car’s transmission) can make the fluid gritty, greatly reducing its ability to provide smooth operation.

Manual

Manufacturer guidelines vary, but most recommend that you change the transmission fluid between 30,000 and 60,000 for standard-use vehicles. For heavy-duty vehicles, that interval shortens to every 15,000 miles. Your vehicle’s manual will tell you what type of oils/fluids to use. If the fluid is allowed to degrade or to become contaminated by debris, it will operate less efficiently and can ultimately shorten the life of your car’s transmission.

Checking the Fluid

In cars with automatic transmissions, manufacturers provide a dipstick to check the transmission fluid. Take care to identify this correctly—avoid the rookie mistake of confusing the transmission fluid dipstick with the crank case oil (engine) dipstick. In many makes and models, these are labeled or color-coded. Check your owner’s manual or ask your mechanic if you are uncertain. Checking fluid levels in manual transmissions can be trickier, and given the number of variations it is recommended to check with your mechanic for the best way to do this—or have your transmission fluid checked during a regularly scheduled service appointment.

We hope these tips will help you keep your vehicle running smoothly and safely!

About Main Line Transmission: Since 1987, Main Line Transmissions has given drivers in the Wayne, Devon, Berwyn, Paoli, Malvern, Exton West Chester and surrounding areas the best transmission service available. Working only on transmissions of every make or model, our technicians are experts through certification, continual training and years of experience.