Why Is My Transmission Fluid Black?

Righter’s Auto Repair advises that your transmission fluid is black because it is long overdue for a change. The transmission fluid should be flushed and refilled every 30,000 miles to ensure that it never turns black. We will discuss the different colors transmission fluid changes throughout its life and why it is important that you never allow the fluid to turn black.


You should always have bright red transmission fluid in the transmission. The fluid should also always be translucent, i.e., you can see through it. This is a sign that the transmission fluid is clean, fresh, and has not oxidized. It is also a sign that the transmission fluid is properly protecting your transmission. The other thing red transmission fluid does is help the transmission change gears.


Even if the fluid is orange or light brown, it still does not need to be changed. The transmission fluid is starting to change colors because it is getting older, but it is still okay if it is light brown or orange. The fluid should also still be translucent at this stage. This fluid can remain in the transmission for a little while longer. This being said, you are on the road to a transmission fluid flush and refill.


Once the fluid turns brown, it is time to change it. This is the time when the fluid also starts to oxidize. Oxidation means that the fluid fills with tiny air bubbles that prevented from protecting the transmission. Consequently, this oxidation will cause the transmission fluid to lose its translucency. You will no longer be able to see through the transmission fluid and the gear shifts will start to get rough.


As the fluid continues to age and oxidize, it will turn black. At this point, rather than protecting the transmission, the fluid is damaging it. It is depositing gunk throughout the transmission and causing the transmission to overheat. In fact, your transmission may it so hot that you can smell the burning odors coming from underneath your automobile. The transmission will also struggle to shift gears.


Aside from black, you never want to see pink transmission fluid, either. Pink transmission fluid means that the fluid is mixing with coolant. This happens when there is a severe leak between the two systems in your engine. The diluted fluid will damage the transmission.

Righter’s Auto Repair in Lansing and Grand Ledge, MI, would be happy to help, so bring us up today if it has been over 30,000 miles since you last had your transmission fluid changed.

Photo by PongMoji from Getty Images via Canva Pro

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