How to Check Transmission Fluid in a Semi-Truck – What Color Should It Be?

some ways to check transmission fluid

If you’re a truck driver, then you know that it’s important to keep your truck in good working condition.

One of the most important parts of your truck is the transmission, so it’s important to make sure that the transmission fluid is in good shape.

In this blog post, we’ll teach you how to check the transmission fluid in a semi-truck and tell you what color the fluid should be.

Keep reading for more information!

What is Transmission Fluid?

Transmission fluid is a type of hydraulic fluid that is used to power the transmission in a vehicle.

The fluid is pressurized by the transmission pump and then used to engage the gears in the transmission.

The transmission fluid also helps to cool and lubricate the transmission, making it an essential part of the vehicle’s cooling system.

Over time, the transmission fluid can become dirty or low, which can cause problems with the transmission.

For this reason, it is important to check the level and color of transmission fluid regularly and to have it flushed and replaced as needed.

How to Check Transmission Fluid?

Checking the transmission fluid in your semi-truck is an important part of preventative maintenance.

By keeping the fluid clean and at the proper level, you can help to prolong the life of your transmission and avoid costly repairs.

The first step is to locate the dipstick. On most trucks, it will be located near the edge of the engine compartment, on the passenger side.

Once you have found the dipstick, wipe it clean with a rag and reinsert it into the transmission.

Then, remove the dipstick again and check the level of the fluid. If it is low, add new fluid until it reaches the full line on the dipstick.

Be sure to use the type of fluid specified by your truck’s manufacturer.

Finally, replace the dipstick and close the engine compartment.

By following these simple steps, you can help to keep your transmission in good working order.

What Color Should the Transmission Fluid Be?

When checking the transmission fluid, it is important to note the color of the fluid.

  • Fresh, clean transmission fluid should be bright red or translucent red in color.
  • If the fluid is dark brown or black, it may be an indication that the transmission is in need of service.
  • In addition, if the fluid is low or if there are any leaks, it is important to have the issue addressed as soon as possible.

By taking care of the transmission, you can help to ensure that your vehicle runs smoothly for years to come.

1- Red Color Transparent Fluid

New transmission fluids should be bright red and transparent in color.

So, if your truck’s transmission fluid is red in color, it means that the fluid is in fresh good condition and does not need to be changed.

2- Light Brown or Semi-Transparent Fluid

Your automatic transmission fluid changes its color after running for a while. But if it is still in a light brown or semi-transparent color, it means that the fluid is still good but may need to be changed soon.

This color and the right balance will not cause any significant issues with your transmission system and if you continue using it it’s still safe.

When your fluid is light brown or reddish, experts recommend that you check it on a regular basis.

3- Dark Brown or Black Opaque Fluid

The light brown color of the transmission fluid changes to dark brown and opaque after some usage.

If your truck’s transmission fluid turns out to be dark brown or black in color, this will generally mean that the fluid is dirty contaminated and old – and it needs to be changed as soon as possible.

This color transmission fluid is not effective in offering the system enough lubrication.

This means if you continue to use it, you will start to experience transmission problems or even complete transmission failure.

Here the recommended action is to flush out the old fluid and change it with the new transmission fluid as soon as you notice it has turned black.

4- Extremely Dark Brownish Black and Burnt

This color transmission fluid indicates that the transmission system is in a very bad condition and is close to failure.

The burnt toast smell that accompanies this color also signifies the same.

So, in this case, you will need to get your transmission system checked by a professional as there may already be some serious issues and damages made.

It is recommended that you do not use this fluid and change it with a new one as soon as possible.

If there are any damages, get them fixed by a professional as well before changing the fluid.

5- Light Pink Transmission Fluid

This color is seen when the anti-freeze mixes with the transmission fluid.

It is an indication that there may be a crack or hole somewhere in the cooling system which is causing the anti-freeze to mix with the transmission fluid.

This can cause serious damage to your transmission system and needs to be fixed immediately.

Get your transmission system checked by a professional as soon as you notice this color in the fluid.

type of color for transmission fluid

Can Transmission Fluid be Yellow in Color?

Yes, it is normal for some transmission fluid manufacturers to make their fluid yellow, green or blue in color. These are actually dyed to make them look different from other truck fluids.

However when the fluid oxidizes it may turn some brownish or dark mustard yellow which is still considered to be in good working condition.

If you have any confusion it’s good to check the level and quality of the fluid according to the manufacturer’s recommendation to ensure that it is still effective.

Why is My Automatic Transmission Fluid Clear?

Generally, the transmission oil will look like a red tint on the dipstick when it is new.

But over time, due to oxidation and heat, the color of the fluid will change and it will become less transparent.

When this happens, it is an indication that the fluid has broken down and is no longer effective.

When Should You Change Your Transmission Fluid?

The best time to change your transmission fluid is every 2 years or 30,000 miles driven – whichever comes first.

However, if you use your truck for towing or heavy hauling, then it’s recommended that you change it more frequently.

Final Thoughts

Transmission fluid is important for the proper functioning of a vehicle’s transmission.

The fluid helps to cool and lubricate the transmission, and it also helps to clean away any debris that may have built up over time.

It’s however important to check the transmission fluid regularly and to change it when it starts to look dirty or dark.

If you notice any unusual colors or smells, it’s best to get the transmission system checked by a professional as there may already be some serious issues.