How to Check Transmission Fluid

Our Family Handyman automotive expert will show you how to check the transmission fluid in your car to prevent damage.

Engine oil isn’t the only fluid in your car that needs to be checked and changed. Transmission fluid is another important one. You can check, top off and change your transmission fluid at home, but a transmission fluid flush is usually best left to the pros. Here’s why and how to check your transmission fluid.

Why To Check Transmission Fluid

Transmission fluid lubricates the parts in your transmission and helps to disburse heat. If that fluid is too low or too old, it can’t do its job.

Driving with low transmission fluid can cause shifting problems and transmission damage. Repairing or replacing a damaged transmission is expensive — it can cost thousands.

Fortunately, DIY transmission fluid checks are quick and easy, so you can maintain optimal performance and prevent damage on the road. All you need to check transmission fluid is a clean shop rag.

When To Check Transmission Fluid

Your owner’s manual should provide maintenance guidelines by mileage or time, including recommendations for when to change transmission fluid. However, levels can get low before the fluid gets old. Most shops will check your fluid levels when you go in for an oil change, but it’s a good idea to check them yourself more often than that.

It’s recommended to check your car’s main fluids monthly. This includes checking your engine oil, power steering fluid and transmission fluid. If you put a lot of miles or wear and tear on your car, it doesn’t hurt to check more often.

Other fluids you might want to check include windshield washer fluid, coolant and brake fluid.

How To Check Transmission Fluid Step-by-Step

  1. Locate the transmission dipstick in the engine compartment.
    1. If you drive a new vehicle, you may not have one. In that case, ask your shop to check your transmission fluid during your next oil change.
  2. Start the engine and let it run for at least three minutes to warm up the fluid.
  3. Pull the dipstick, wipe it clean with the rag and put it back in the dipstick tube.
  4. Pull the dipstick again and check the level.
    1. It should be between the two marks. If the level is too low, add more fluid.

If you need to add fluid, be sure to get the right kind. It should be listed in your owner’s manual. Using the wrong kind of transmission fluid can harm your transmission.

While purchasing transmission fluid, pick up a transmission funnel to make pouring cleaner and easier. Place the funnel in the transmission fill tube and add a pint of fluid. Check the level as outlined above, and add a second pint if needed.

If you check your transmission fluid and keep it at the right level, your transmission should last for the lifetime of your engine. Your vehicle will thank you.