How to Check Transmission Fluid

Why is checking transmission fluid so important? Well, how else are you going to learn about the health of your transmission? Not only can checking the fluid tell you a lot about your transmission, it can also help you decide on what steps you can take to ensure it continues to run like a charm. Checking transmission fluid should be part of a routine basis and not just something you do when you start experiencing problems, because once you notice a problem it probably means there has already been some damage done to your transmission. It can also help you to diagnose smaller problems such as leaks, low fluid levels, and worn out fluid so that you can save some cash and a troublesome trip to the repair shop. Without further ado, here’s how to check transmission fluid the right way.

How to Check Transmission Fluid

What you are going to need before you start is a clean towel that is white or preferably something light, and a car with a transmission to check. (Let’s not leave that out of the equation.) If you are going to add fluid then you will need the recommended fluid specified in the owner’s manual and a funnel. Once you’ve got all that you’re going to have to know where the transmission dipstick is located. You are probably familiar with the oil dipstick already, which measures the car’s engine oil. Well, the transmission dipstick works in the same way but instead it measures the transmission fluid. Pretty simple right?

You can usually find the transmission dipstick situated near the oil dipstick and it should be labeled for easy access. If your car has front wheel drive it should be sticking out of the transaxle near the front. If you can’t seem to find it, take a look at the owner’s manual for more details. Once you have located the dipstick you are ready to begin, we can learn how to check transmission fluid now!transaxle and transmission fluid dipstick - how to check transmission fluid

***This applies differently to some newer cars***

Checking Transmission Fluid

What You’ll Need:

1. As we’ve mentioned you need to warm your car up first before you go about checking the fluid. That’s because fluid expands in heat and it needs to be under normal operating temperatures if you are going to want accurate results. If you check the fluid while it’s cold it might appear that you have low levels when really it’s only because the fluid hasn’t expanded. And while you think your car has low fluids you might add more which can cause it to overfill. Overfilling on transmission fluid can cause it to push out of the case vent and filler tube, and can cause seals to blow. It can also cause your transmission to slip and act unstable.

So park your car on a level surface, prop the hood up, and start your baby in either Neutral or Park. Let it run for a few minutes to get the juices flowing. If you are checking a Honda, you will need to turn off the engine after it has warmed up, at which point you will have 60-90 seconds to check the fluid. For most other vehicles you car needs to keep running.

2. Once your car has warmed up, remove the dipstick from the cylinder and wipe it down with the towel. You are going to want to inspect the towel for a few signs:

  • Color: New transmission fluid is a bright, transparent red and depending on how long it has been since your last service the fluid should reflect it in color. A darker red to a light brown is normal and indicates age, which is normal for running vehicles. A color closer to a dark brown is a warning sign and means you should get the fluid changed soon, which we will explain in another article. A color that is black usually means transmission problems have already occurred and that’s the last thing you want. Be sure the fluid does not get to this point!
  • Smell: We’re not saying that your fluid should smell like roses and daisies but normally it should not smell like burnt toast. New fluid is usually odorless and smells decent, but transmissions that have developed problems will produce fluid that gives off a burnt smell. Burnt fluid is a clear sign that your car needs to be serviced and neglecting to do so could result in further damage.
  • Consistency: Over time fluid may appear to be thicker which is normal but fluid that is healthy should show no signs of trouble. Fluid should be clear of any contaminants such as large particles and metal shavings. If you do find any it could mean a number of things, such as worn gears or a damaged torque converter. If you find that the fluid is bubbly or foamy then that means there is too much fluid or the wrong fluid was used.

how to check transmission fluid colors how to check transmission fluid colors

3. If everything checks out and the color, smell, and consistency is okay then you can re-insert the dipstick back into the transmission. Now we are going to remove it again to gauge the fluid levels this time.

The dipstick will have two lines on it to mark the upper and lower limit. Sometimes it will be labeled “Full” and “Add” to make it easier on you. Check to see whether the fluid is between the two lines, if it is then it means there is enough fluid and you don’t have to add any more. But if the fluid is under the “Add” or lower line then you need to add more. Remember, low fluid levels are the leading cause of most transmission problems.

***If the level is way below the “Add” or lower line then this could mean you have a leak. Look on the driveway and under your car for any signs of leaks. If there is a leak you are going to need to find what’s causing it and plug it up. If it isn’t a leak then you can proceed to adding more fluid.***

  • With your funnel you are going to want to insert that into the opening that you pulled the dipstick out of. Make sure it is secure. Afterwards you need to take your new transmission fluid (that is specified in the owner’s manual) and pour it into the funnel in small amounts. Do it slowly too, we don’t want to overfill! We are going to add just enough for the level to be in between the two lines. Check the dipstick for fluid levels periodically and make sure it isn’t too much. Once the level is in between the two marks you can re-insert the dipstick securely, lower the hood, and turn off the engine. Bada-bing you’re done!

And that’s how to check transmission fluid. Not too hard right? It definitely beats going to the repair shop every time and having to pay for a job that takes less than five minutes. Checking transmission fluid yourself is the best way to find small problems that are affecting your car, and you should do it on a routine basis to make sure the transmission is doing okay. Always be sure to check the transmission fluid before you take it into a repair shop, because if you can’t fix the problem yourself at least you will have a good idea of what’s causing the problem. Don’t let a mechanic sell you a bunch of services and repairs you don’t need!

Below is a quick video on how to check transmission fluid.

***Some newer cars don’t have a transmission dipstick. The only way to check the fluid in these cases is to bring it in for a technician to look at, where usually they check the fluid through a plug on the side of the transmission or by checking the car’s computer.***