Much like how your car's engine requires clean oil, your transmission requires clean transmission fluid in order to function properly.  If your car is having problems with the transmission, the fluid can tell you what is happening under the hood.  By understanding the different smells and colors of transmission fluid, you can diagnose how serious the problem is and whether or not you need transmission repair.

Clean Fluid With No Odor

Ideally, your car's transmission fluid will be red and clear and not have any smell to it.  If you check the fluid and it meets those three criteria, you have nothing to worry about when it comes to the fluid.  That does not mean your transmission is functioning properly with 100% certainty though.  There could be other issues, such as a transmission fluid leak, that are causing problems.

Brown Fluid With A Slight Odor

If the fluid has started to slightly turn brown and has a faint burnt odor, you should have your car's transmission looked at.  There is a good possibility that the problem was caught early, and an auto shop will be able to get to the bottom of the problem with ease.  Keep in mind, it is possible to have discolored fluid if the previous transmission fluid was not properly flushed.

Dark Brown Fluid With A Stronger Odor

When the color and odor start getting worse, to the point where the brown color is noticeable and the odor is distinct, you need to have the fluid flushed immediately.  Your transmission could have a serious problem with it that could lead to transmission failure.  Ignoring the problem could leave you stranded on the side of the road.

Black Fluid With A Terrible Odor

Transmission fluid turns black when it starts burning; this is a huge sign that there is a problem. You may even smell the burning odor while you are in the car. This problem could potentially lead to the transmission needing to be completely rebuilt.  This is one of the most expensive repairs that you could possible need for a transmission, and it is avoidable if you pay attention to the transmission fluid. 

If you want to extend your transmission's life, then you need to pay attention to what the transmission fluid is saying. While small problems are not preventable, paying attention will help you catch the issue before it gets to a point where it causes serious damage to one of the most vital parts of your car.