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How To Add Transmission Fluid: The Complete Guide

Fresh Transmission Fluid is Critical To a Smooth Operating Vehicle

Adding transmission fluid to a car

Adding transmission fluid can sound daunting, but it is actually quite simple. Save a trip to the auto shop and some money by following this easy guide on how to add transmission fluid. We will also outline how to check your fluid levels, which you should do regularly to catch any potential problems early on.

Transmission fluid is what keeps your car’s manual or automatic transmission running smoothly, allowing you to properly shift gears. What you will need to check or fill your transmission is a clean rag or paper towel, a long funnel, and your car’s specific transmission fluid. Every vehicle is different — check your owner’s manual to see what type of fluid your car needs.

How To Check And Add Transmission Fluid 

You must check your fluid levels while the car is warmed up to operating temperature. Some cars even require that you check it while the car is on and running. Refer to your owner’s manual to see if the car should be on or not. Regardless, the engine should at least be warmed up. 

Your car should also be parked on a level surface to ensure you get an accurate reading on your fluid level. Put the vehicle in park and make sure your emergency brake is set.

(Before you get started, it’s worth noting that a few vehicles, such as some Ford-F150s, don’t provide under hood easy access to check your transmission fluid. Instead, on these vehicles, you must check and fill the transmission fluid by opening a bolt on the transmission itself. This is beyond the scope of this article.)

1. Locate the hood release and open your hood. The hood release can usually be found by where your left knee rests while driving. If you cannot find it, refer to your owner’s manual.

2. Locate the transmission dipstick. The transmission dipstick will have either a yellow/orange handle or it will be marked with writing or an icon. Do not confuse the transmission dipstick with the oil dipstick; they look very similar. If you are not sure, again, refer back to your owner’s manual.

3. Pull the transmission dipstick out and wipe it clean. You will need to wipe the dipstick clean so that you can properly measure the fluid level, once you reinsert it.

4. Reinsert the dipstick back to its original location and remove it again. This will show you your fluid level.

5. Check the fluid level on the dipstick. The fluid should be between the hash marks on the dipstick. If it is below the lower hash mark, you will need to add more fluid.

How To Add More Transmission Fluid

Next, it is time to add more fluid. First, make sure you check your owner’s manual to make sure you have the correct fluid for your specific vehicle and transmission. This is extremely important! 

1. Place the funnel in the transmission check tube. The funnel will take the place of the dipstick. 

2. Add the fluid in very small increments. It is important to add only a little bit at a time. You need to be careful about how much you are adding because you actually do not need that much. Remember, you can always add more, but it will be extremely difficult to take fluid out if you overfill the transmission.

3. Recheck the level with the dipstick after each pour. This will allow you to see how much more you need, and keep you from overfilling. When you reach a level that reaches the top hashmark, or the full marker on the dipstick, remove the funnel and return the dipstick to its original spot.

Frequently Asked Questions

Do you leave the car running when adding transmission fluid?

It depends on your vehicle. Check your owner’s manual to see whether you should leave your car running or whether you should turn it off. Typically, your engine needs to at least be warmed up to operating temperature before checking your fluid level.

Can you add transmission fluid through the dipstick?

In many vehicles, you will need to remove the dipstick and insert a funnel into the tube in order to add the transmission fluid. Consult your owner’s manual.

How much transmission fluid do I add?

Use the markers on the dipstick to check how high the fluid level is. Use the dipstick to check several times as you are adding the new fluid. Once the fluid is in between the markers on the dipstick, you should not need to add any additional fluid.

If your transmission fluid is completely out or extremely low, the typical amount to add is around 9-13 quarts of fluid. Again refer to your owners manual for exact numbers for your vehicle and transmission.

What happens if you put in too much transmission fluid or overfill it?

If you add too much fluid, the excess fluid can cause the pressure to increase within the transmission. This may cause the gears to grind or your transmission to overheat.

This is why it is important to add the fluid in very small increments, and to continuously check the level with the dipstick as you are filling the transmission.

How do you know when you need to add transmission fluid?

If your car is having problems with shifting, you likely need to add transmission fluid. If your car jerks while shifting gears or if you notice a delay/erratic shifting, the problem might be that the transmission fluid is low. Some other symptoms are a grinding or screeching noise when you are shifting, a burning smell while shifting, or if your car pops out of gear.

About Rhea Jha

Rhea is currently pursuing a B.A. in Journalism and History at Penn State University. In her downtime, you can find her enjoying a cheese board, petting her dog, or probably watching Chopped.