Decoding Your Transmission Fluid: What it Means for Your Car
Smooth shifting and easy acceleration rely on transmission fluid. Not only does having adequate fluid in good condition help improve your car’s performance, it also helps extend the life of your transmission. Because of its key role in your car’s operation, there’s a lot you can tell from the color and condition of your transmission fluid. It’s helpful to know what transmission fluid does for your car, how to check it, and what its condition says about your vehicle overall.
What Does Transmission Fluid Do?
Your car’s transmission fluid serves two key roles: lubrication and pressurization. Manual transmissions are more mechanical and mainly rely on fluid to keep moving metal components lubricated. This prevents excess wear and tear, as well as minimizing heat from friction. On the other hand, automatic transmissions use fluid for both lubrication and pressurization that helps facilitate gear engagement. Fluid flow is directed through the transmission by solenoids, which are small valves that open and close depending on which gear is or needs to be engaged. In either type of transmission, it’s essential that there’s always adequate fluid and that it’s in good condition.
What Your Transmission Fluid Says About Your Car’s Condition
Many vehicles have a dipstick you can use to check your transmission fluid. Check your owner’s manual for information about how to locate your transmission fluid dipstick (if your car has one), fluid servicing intervals, and the type of fluid to use in your vehicle. When you check your transmission fluid, the color and consistency can tell you a lot about whether the system is operating smoothly or if there’s a looming repair.
Bright Red Coloring: Fresh Fluid and a Healthy Transmission
Most transmission fluid is bright red right out of the container, though some may also be blue or purple. If the transmission fluid in your car is bright red, it’s an indication that it’s still fresh and the system is operating smoothly. In general, there’s no need for a mechanic to inspect the system and likely no repairs necessary.
Dark Red & Thickened: Contaminated Fluid That Should Be Replaced
A deeper, darker red color indicates there’s some contamination buildup. The fluid is not fresh, but the system is in good condition overall and it’s not urgent that you schedule a transmission service right away. Darker shades of red, especially alongside the fluid being noticeably thicker, tells you contaminants have been picked up over time. The thicker and darker the fluid, the sooner you should consider scheduling a fluid replacement service.
Light Brown Coloring: Old, Oxidized Fluid That Should Be Replaced
If your transmission fluid is light brown, it indicates it’s dirty and has started oxidizing. There are two key things that lead to oxidization of transmission fluid: exposure to oxygen and extreme temperatures. In particular, high temperatures commonly cause oxidized fluid, leading to a faster breakdown. Though it’s not urgent, oxidized fluid should be replaced soon, especially if you haven’t had a transmission service in the last 50,000 miles.
Dark Brown or Black Coloring: Limited Lubrication & Chance of Overheating
Transmission fluid that looks dark brown or black is old and contaminated. At this point, internal components are likely under-lubricated, leading to more wear and higher temperatures. If the fluid is black and tarry, there’s an even greater chance that your transmission is overheating. You’ll likely notice changes in performance like slipping or hesitation during acceleration. Aside from needing a transmission fluid replacement, you may also need another repair to get the system running efficiently again. Avoid driving further as much as possible and schedule a service with your mechanic.
Foamy & Pink Coloring: Fluid Contaminated with Water or Coolant
When transmission fluid turns pink and becomes thin or foamy, it indicates water or coolant in the system. Often, this is due to a leaky radiator or coolant lines that go through the transmission. Check your coolant level — if it’s low, a mechanic should do an inspection to locate the source of the leak. In any case, thin, foamy, pink transmission fluid needs to be replaced as soon as possible. More serious cases may mean you need a transmission rebuild or replacement, if extensive damage is already done within the system.
Need Help with Your Transmission? Trust Your Local Chicagoland AAMCO
Dealing with strange-colored or otherwise abnormal transmission fluid? Noticing changes in performance that point to transmission trouble? One visit to the expert mechanics at your local AAMCO and notice a smoother ride and more efficient transmission each time you’re behind the wheel. Schedule your appointment with us today!
For more tips on maintaining your vehicle, check out our blog post on Transmission Maintenance Tips.
