Perhaps you’ve noticed when changing your transmission fluid that it seems to change color. Indeed, there are a variety of colors that could be coming out of your vehicle, leaving you scratching your head and wondering what in the world’s going on!
The short answer is that transmission fluid oxidizes, which is a chemical reaction sometimes triggered by tiny air bubbles that causes the loss of electrons. The oxidation process causes the fluid to change color. This is why it’s recommended to have your transmission fluid changed every 30,000 miles. Fresh transmission fluid is needed to help your transmission shift gears.
But do the colors mean anything? What can you infer from the color of your transmission fluid?
Red and Transparent
Fresh transmission fluid is bright red and somewhat transparent. It’s ready to protect your vehicle’s transmission as well as all of its moving parts and also works as a hydraulic fluid, helping the transmission change gears. If your car or truck has fresh, clean fluid, you don’t have to change it. The color red is a good sign.
Brown or Orange and Transparent
The first stage in the oxidation process turns the transmission fluid brown or sometimes orange, but it doesn’t necessarily cloud it. Transmission fluid that looks like this is still doing a good job and doesn’t need to be changed yet, so long as the brown is a light color. You shouldn’t notice any problems shifting gears or faults in the transmission.
However, if the fluid turns dark brown, it needs to be changed. This fluid is losing its viscosity, the degree to which it can resist flow under an applied force, and isn’t protecting your transmission any longer. You may find that you have difficulty shifting gears, and your transmission could overheat to boot.
Black and Opaque
If you continue to put off changing your transmission fluid, it will turn black and opaque. Now your transmission could actually be damaged, as the fluid is fully oxidized and doing nothing to help your vehicle. In fact, it’s even depositing a grimy substance throughout your vehicle’s system and needs changing as soon as possible. At this rate, you could even find yourself stranded in a non-functional vehicle.
Pink
Pink is the color you should most dread, and if you see it in your transmission fluid, you need to get it to a mechanic ASAP. Pink fluid means that there’s a leak in your transmission, causing it to fill with engine coolant. The damage done means that your transmission needs replacing.
The Meaning of These Colors
The moral is that you really need to heed that recommendation to change your transmission fluid every 30,000 miles. It’s too easy for damage to occur along with oxidation, especially excessive oxidation, so remember to bring your car or truck to a mechanic to have it done. Your mechanic can also perform general maintenance during this time to ensure that your vehicle lives a long life.