Check your transmission fluid with the engine running, the car on level ground, and the transmission in Park or Neutral
Transmission fluid keeps your transmission cool and lubricated. Over time it breaks down, gets dirty, or leaks out — and low fluid is one of the most common reasons transmissions fail. Checking it takes about five minutes and costs nothing. You do this while the engine is warm and idling, which is different from checking engine oil, so read through the steps before you start.
The basic process: locate the transmission dipstick under the hood, pull it out, wipe it clean, reinsert it fully, pull it out again, and read the fluid level against the markings on the stick. If the fluid is low, dark, or smells burnt, you have found a problem worth addressing soon.
Key Takeaways
- Check transmission fluid only when the engine is warm and running, with the car parked on level ground and the transmission in Park or Neutral.
- The transmission dipstick looks similar to the oil dipstick but is usually located in a different spot under the hood — your owner's manual shows the exact location.
- Wipe the dipstick clean, reinsert it all the way, then pull it out again to get an accurate reading of the fluid level.
- Transmission fluid that is dark brown or black, smells burnt, or feels gritty means the fluid needs to be changed or the transmission needs inspection.
Locate the transmission dipstick under your hood
Open your hood and look for the transmission dipstick. It is a thin metal rod with a handle, similar to the oil dipstick, but usually located in a different spot. On front-wheel-drive cars, it is often toward the back of the engine bay. On rear-wheel-drive cars, it may be on the driver's side or passenger's side depending on the model.
If you cannot find it by looking, check your owner's manual — it will show a diagram of the engine bay with the dipstick labeled. Some newer cars do not have a transmission dipstick at all; if yours is one of them, you will need to have the transmission fluid checked at a shop using a different method.
Prepare the car and warm up the transmission
Park on level ground and leave the engine running. The transmission fluid needs to be warm — this gives you an accurate reading. Let the engine idle for a minute or two after you park. If you have just driven the car, the fluid is already warm and you can check it right away.
Keep the transmission in Park (if automatic) or Neutral (if manual) while you check. Do not turn off the engine. If you turn it off, the fluid will cool and the reading will be wrong.
Pull out the dipstick and wipe it clean
Grasp the handle of the transmission dipstick and pull it straight out. You may need to pull firmly — it is usually a tight fit. Wipe the entire stick clean with a paper towel or lint-free cloth. Any dirt or old fluid on the stick will make the reading hard to see.
Once it is clean, look at the markings on the stick. Most transmission dipsticks have two sets of marks: one for when the fluid is cold and one for when it is warm. Since you are checking with the engine running, you will use the warm marks.
Reinsert fully, then pull out to read the level
Push the dipstick back into its tube all the way until it seats. You should feel it click or bottom out. Then pull it straight out again. This second pull gives you the true reading because the fluid has coated the stick evenly.
Look at where the fluid line sits on the stick. It should be between the minimum and maximum marks for the warm range. If it is at or below the minimum mark, your transmission is low and needs fluid added. If it is above the maximum mark, you have overfilled it, which can also cause problems.
Understand what the fluid color and smell tell you
While you have the dipstick out, check the color and smell of the fluid. Healthy transmission fluid is bright red or pink and has a slightly sweet smell. If the fluid is dark brown or black, it has broken down and needs to be changed. If it smells burnt or acrid, the transmission has been running too hot.
Rub a small amount of fluid between your fingers. It should feel smooth and slippery. If it feels gritty or grainy, metal particles are in the fluid, which means internal wear is happening. Any of these signs — dark color, burnt smell, or gritty feel — means the transmission should be inspected by a shop soon, even if the level is correct.
Add fluid if the level is low
If the dipstick shows the fluid is low, you can add transmission fluid yourself. First, check your owner's manual or the cap under the hood to find out what type of fluid your transmission uses. Different transmissions need different fluids, and using the wrong type can damage the transmission.
Once you have the correct fluid, remove the transmission fill cap (usually labeled on top of the transmission) and pour fluid in slowly. Check the level with the dipstick after adding a small amount, then add more if needed. It is easier to add a little at a time than to overfill and have to drain some out. Replace the cap when you are done.
Frequently Asked Questions
Can I check transmission fluid with the engine off?
No. The fluid expands as it warms up, so a cold reading will show the level as lower than it actually is. Always check with the engine running and warm. If you check when cold, you may add fluid you do not need.
What if I cannot find the transmission dipstick?
Some newer cars, especially those with continuously variable transmissions (CVTs) or sealed automatic transmissions, do not have a dipstick. Check your owner's manual to confirm. If there is no dipstick, a shop will need to check the fluid using a scan tool or by removing a plug on the transmission itself.
How often should I check transmission fluid?
Check it once a month as part of routine maintenance, or any time you notice the transmission shifting hard, slipping, or making noise. If you see fluid leaking under the car, check the level right away.
Is transmission fluid the same as transmission oil?
Transmission fluid and transmission oil are the same thing — the terms are used interchangeably. It is not the same as engine oil. Each type of fluid is designed for its specific job, so never substitute one for the other.
What should I do if the fluid smells burnt?
A burnt smell means the transmission has been overheating. This can happen from low fluid, a failing cooler, or internal problems. Have the transmission inspected by a shop as soon as you can. Continuing to drive with an overheating transmission can cause permanent damage.