What Can You Learn from the Color and Smell of Automatic Transmission Fluid?

The color and smell of your automatic transmission fluid (ATF) can give you an indication of the overall state of your transmission, and help in diagnosing transmission problems like low fluid levels, leaks, and worn out fluid.

Checking the state of your ATF should be done routinely before you even notice a problem. So, how do you check the color and smell?

First, it is recommended that you warm up your car before checking the fluid. The fluid should be under normal operating temperatures to ensure accurate results. The car should be parked on a level surface.

Keep the engine running, and locate the transmission dipstick (usually next to the engine dipstick). Pull it out of the filler tube and inspect the color and smell of the fluid on the end of the dipstick. You may also place a few drops of the fluid on a clean white sheet of paper to achieve a better color reading.

What the Color Says About Your Automatic Transmission Fluid

New transmission fluid is bright red and transparent, and depending on the last time you had your last service, the ATF should reflect it in color. Keeping your fluid in this condition will significantly reduce the risk of having serious transmission problems. Other color variations include:

• Light brown, semi-transparent: The fluid is still in good condition and does not need changing
• Dark brown, opaque fluid: Any change that is closer to dark brown indicated that the fluid is old and dirty. It should be changed as soon as possible before it causes serious damage, as this fluid condition tends to increase heat within the transmission, making it more likely to fail. You should also change the filter.
• Very dark or black fluid: Very dark color means that the fluid is old, dirty, and oxidized (if there is a burnt odor). It could also indicate some damage inside the transmission. If the transmission is working properly, you should take action immediately by changing the fluid and filter. If the transmission is damaged, a rebuild may be needed.

What The Smell Says About Your Automatic Transmission Fluid

New fluid is odorless, but transmissions that have developed internal problems that cause overheating will produce oxidized fluid with a burnt smell. The result is poor lubrication, increase friction and heat, and excessive wear or damage to internal components. In most cases, burnt smelling ATF means that internal damage has occurred, and your transmission needs to be serviced.

For professional transmission maintenance and repair, bring your car to Pro-Tech Transmission. Our technicians will check the condition of the fluid, computer system codes, the operating condition, and a bunch of other things to ensure your transmission outlasts the life of your car.