Does Transmission Fluid Get Dark When It’s Old?

Yes, Mark’s Auto Service advises that transmission fluid darkens in color as it ages. In fact, the color of the fluid can be an indication of when it needs to be changed. Generally, you should plan to have your transmission fluid flushed and refilled every 30,000 miles. This ensures you always have clean transmission fluid in the transmission ready to protect it and help it shift gears.


Initially, transmission fluid is bright red and translucent. This is a sign of healthy transmission fluid that is providing excellent protection and also assisting in the transmission’s gear shifts. Transmission fluid isn’t just a lubricant; it’s also a hydraulic fluid. If your vehicle’s transmission fluid is red and translucent, it does not need to be changed at this time because it is in excellent condition.


Once the transmission fluid starts to get a little bit older, it will turn orange or light brown. It should still be translucent at this stage. If it is, it does not need to be changed quite yet. The orange fluid is still doing a good job of keeping the transmission protected and cool. It is also doing a good job of helping the transmission shift through the gear cycle. You’re still okay for the time being.


Once the transmission fluid turns brown, it needs to be changed right away. The reason why transmission fluid darkens as it gets older is that it starts to oxidize. What this means, is that the fluid starts to fill up with tiny air bubbles that affect its ability to do its job. The brown transmission fluid also loses its translucency. It will be opaque. Schedule a transmission fluid change right away.


If you fail to do so, the transmission fluid is going to turn black, and rather than help it, it will start to damage it. This oxidized fluid will cause the transmission to overheat and shift the gears roughly. In fact, the transmission may struggle to shift through the gear cycle because the fluid is harming it.


Finally, you never want to have pink transmission fluid in the transmission. If the red fluid turns pink, it is being mixed with engine coolant. This happens if there is a serious leak developing between the cooling system and the transmission. This diluted fluid will damage the transmission.

Mark’s Auto Service in Loves Park and Loves Park, Belvidere, Roscoe, and Rockford, IL, is here to help, so call us today if it has been 30,000 miles since you’ve had your transmission fluid changed.

Photo by PongMoji from Getty Images via Canva Pro

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