Why Does Transmission Fluid Change Color As it Ages?

Transmission fluid changes color as it ages because it oxidizes. What oxidation means is that it gets tiny air bubbles in it and this reduces its effectiveness. Generally, it is recommended that you have your transmission fluid changed every 30,000 miles. This ensures you always have fresh fluid in the transmission ready to protect it and help it shift gears. CAR FIX can change your transmission oil when it needs it. Here are the stages of colors that it goes through throughout its life.


New transmission fluid is bright red and easy to see through. This fluid is viscous and does an excellent job of protecting the transmission and all of its moving parts. It also works well as a hydraulic fluid to help the transmission change gears. This fluid is fresh, clean, and does not need to be changed. Red and translucent transmission fluid is considered to be the healthiest for your automobile.


As transmission fluid gets older, it will turn light brown yet remain translucent. While it is in this stage, it is still okay and does not need to be changed. Light brown and translucent transmission fluid is still doing an excellent job of protecting the transmission and helping it shift gears. In some cases, the fluid may look more orange than light brown. Either way, the fluid is still okay.

Once the fluid turns brown to dark brown, it is beginning to oxidize and needs to be changed. This fluid is losing its viscosity and you are running the risk of overheating your transmission if you continue to drive with the transmission fluid in this condition. This fluid is also not as capable of helping your transmission shift gears and it is definitely not protecting the transmission.


If you ignore your transmission fluid until it turns black, you will do a serious disservice to your transmission. In fact, you may even damage it. Black transmission fluid is fully oxidized, opaque, and is unable to protect the transmission and help it shift gears. This transmission fluid is depositing grime throughout the system. Have your transmission fluid changed ASAP.


Finally, your transmission fluid should never be pink. If it is, your transmission is in deep trouble. Pink transmission fluid means that there is a serious leak in your transmission and it is filling up with engine coolant. This can cause catastrophic damage to the transmission.

CAR FIX has three locations in Tennessee to serve you. Call our Oak Ridge auto shop if it’s closest to you. Call our Crossville auto shop if that one is closer, or you can call our Cookeville auto shop. We’d be happy to take a look at your transmission fluid and change it if it needs it.

Photo by chat9780 from Getty Images via Canva Pro

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