Why Is Transmission Fluid So Important to Your Vehicle’s Performance and Longevity?

Shade Tree Garage

Just as engine oil is essential for the smooth operation of your vehicle’s engine, transmission fluid plays a crucial role in the functioning of your vehicle’s transmission. When the level of transmission fluid drops for various reasons, it can compromise your transmission. A compromised transmission can lead to a complete transmission failure, which can be an expensive problem for vehicle owners. In this blog post, we delve into the common signs of low transmission fluid to help you prevent a total breakdown of your vehicle’s transmission. 

Understanding Transmission Fluid

Depending on the type of transmission in your vehicle, you may have either automatic or manual transmission fluid. Transmission fluid is a synthetic fluid that is designed to lubricate the gears and components of your transmission, provide hydraulic pressure and friction to the automatic transmission, and control the temperature of this hard-working component of your vehicle. 

Why is Transmission Fluid Low?

While your vehicle’s transmission fluid may naturally burn off over time, it is usually not enough to cause a significant drop in the level. The main reason for low transmission fluid is a leak within the transmission system. Sometimes, the leak may be in the transmission pan or due to a faulty gasket. At other times, the leak may occur somewhere along the transmission line. A slow leak is more challenging to detect because it may burn off in the engine before appearing on the ground beneath the vehicle. Transmission fluid is easy to spot if there is a significant leak due to its bright red color. Older transmission fluid changes color and may appear as a darker red or even brownish hue. 


If you find that your transmission fluid is low, top it up so that it continues to perform its necessary function for the transmission components. If the fluid level continues to be low, it should be inspected by a service professional.

Signs of Low Transmission Fluid

In addition to regularly checking the level of transmission fluid, there are some signs and symptoms that can indicate that your vehicle’s transmission fluid is low. If you are not inclined to check the level regularly, then watch out for these symptoms. 

  • Dashboard Warning Light: If your dashboard warning light comes on, it could indicate that the transmission fluid is low. 
  • Overheating: If the fluid level is low, your transmission is not getting the proper cooling it needs, and this can cause your engine to overheat. This may be accompanied by a burning smell. 
  • Difficulty Shifting Gears: If you are having trouble shifting gears in your vehicle, this could be a symptom of low transmission fluid. The gears require adequate lubrication due to the friction they generate. 
  • Unusual Noises: The transmission can produce various sounds when the transmission fluid is low, including humming, clunking, grinding, or whining noises. Often these noises are caused by grinding parts that lack sufficient lubrication. 
  • Gear Slippage: If gears slip when shifting, this could indicate low levels of transmission fluid. 

When Should Transmission Fluid Be Changed?

Modern vehicle transmissions are more efficient and in some cases, may never require a change of transmission fluid. However, if you do a lot of heavy driving, you might consider changing your transmission fluid every 50,000 to 100,000 miles driven. When checking the fluid level, also look at its color and viscosity. The darker and thicker the fluid, the more urgent the need for replacement. 


If you want your vehicle’s transmission fluid checked or need any repairs done on your vehicle’s transmission system, contact our service professionals at Shade Tree Garage to schedule an appointment. 

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