How to Check Transmission Fluid

There are a lot of moving parts in your vehicle’s transmission. It takes a slippery liquid called car transmission fluid to lubricate those parts and gears and keep them running smoothly. As a vehicle owner, it's a good idea to learn how to check the transmission fluid and know when transmission fluid needs to be replaced. If it does need to be replaced it's a good idea to know the steps on how to change the transmission fluid in case you'd like to change the fluid yourself. Ignoring this really important maintenance task could cause transmission failure and end up costing you a lot of money. The money you could be spending on cool stuff like tacos and waterpark tickets.

More vehicle Maintenance Tips

Select a Topic: Car Battery Care and Maintenance, Brake Fluid, How to Check or Change Your Vehicle’s Oil Flat Tires, How to Measure Tire Tread, Vehicle Warning Lights, How to Check and Change Your Engine Coolant (Antifreeze), When to Change Your Transmission Fluid, Four Signs Your Transmission Fluid Needs to Be Changed

The transmission is grinding or making other strange noises (such as screeching or squealing)
Your car's gearshift is slipping between gears
The vehicle is surging or lurching, not handling smoothly
There is a delay in vehicle movement

Checking Your Transmission Fluid

You check your engine oil level, right? And you get your engine oil changed, right? Well, you should check your transmission fluid too as part of your car maintenance schedule. It’s a very similar process: pull out the transmission dipstick, wipe it clean with a lint-free rag or a paper towel, place the dipstick back in the dipstick tube, and pull it back out to see a clear reading of the fluid level. If your vehicle doesn’t have a transmission dipstick, don’t worry. Check the owner manual to learn when the fluid and transmission filter should be changed and when you should do a transmission flush. A common recommendation is about every 20,000 to 25,000 miles, but it might need changing sooner depending on your vehicle.

The big difference between transmission fluid and oil checks is that you will actually check the transmission fluid while the car is running. Just remember to keep it in Neutral or Park, and set the parking brake for safety. If the fluid level hits below the minimum line on the dipstick, you will need to add more or do a transmission fluid change (keep reading to find out how). Check your owner’s manual to see which kind is recommended for your vehicle. As with any mechanical liquids, be sure to keep dangerous materials in lockup away from kids and animals.

You will also want to check the consistency of the fluid, which should be clear with a pink tint. If the fluid condition looks gunky, it may be a good idea to get the fluid flushed and get a fluid exchange. If you'd like to change your vehicle transmission fluid yourself, keep reading for a step-by-step guide on how to get rid of that old fluid and get some fresh fluid running through your car.

Changing Your Transmission Fluid (Automatic Transmission Fluid)

Make sure the car is off and place it in park. Raise it up securely with a jack stand or a lift. If you don't know how to do this safely, please go to a professional mechanic working at a repair shop. We don't need any accidents, okay?
Lay down some tarp and a 2-gallon (or 8-quart) catch pan under the transmission. This pan is where the fluid you drain will go so be sure to place it accordingly. You'll also want to make sure you're wearing gloves and some safety goggles for this task- transmission fluid can get pretty messy. Completely remove the bolts from one end of the transmission oil pan. Be careful not to burn yourself on any hot surfaces if your car was running recently.
Gradually loosen the bolts on the other end of the pan so that it will begin to tilt. Once the pan is tilted, the transmission fluid should start to drain into the catch pan you set out earlier. Once the majority of the fluid has drained, remove the rest of the bolts and dump the remaining fluid in the catch pan.
Clean both the oil pan and gasket housing with a cleaning solvent. Make sure there aren't any signs of damage like metal shavings left in the oil pan or erosion on the gasket.
Remove the old filter by unscrewing the bolt and attaching it to the transmission. Clean off any residue from the transmission body and replace the old filter with a new one. If you need to replace your filter, check your owner manual to make sure you purchase the correct model for your car.
Remove the old gasket from the oil pan and adhere the new gasket to the transmission pan using oil-soluble grease as a sealer (don't use adhesive). Place the oil pan with the new gasket back against the transmission and tighten all bolts by hand first to secure it to the transmission. Then go back in and tighten all of the bolts by torquing them in a criss-cross pattern, moving across the pan as you tighten to ensure it's locked onto the transmission evenly.
Now that your bolts are secure, lower the car and add the new transmission fluid through the dipstick tube using a funnel. You'll want to reference your owner's manual for recommendations on which kind of fluid you need. This information can also be found with a quick online search. For example, do you need manual transmission fluid or automatic transmission fluid? Is there a specific brand that works best with your car model?
Turn the car on and let it run for a while until the engine is warm. Use the transmission oil dipstick to check the automatic transmission fluid level. If the fluid doesn't reach the appropriate markings on the dipstick, add more fluid. Once the fluid level is adequate, turn the car off and check that there aren't any leaks coming from the transmission pan. Be careful! The car will be hot from running. You can now take it down from any jacks or ramps you were using.
Dispose of the fluid and the catch pan properly. Transmission fluid can be super dangerous for the environment, so you'll want to make sure you take it somewhere with a disposal program. Most auto part stores and mechanics will have fluid recycling programs you can take advantage of to dispose of used oil and drained transmission fluid.

If some visuals would help, we also love this video on how to change transmission fluid. Feel free to check it out for more information.

Changing Your Transmission Fluid (Manual Transmission)

The process to change automatic fluid can be a little more complicated than that of a manual transmission. Look how easy a manual transmission can be!

Jack your car up safely so you can get underneath it to work on the transmission. Place a catch pan underneath the transmission to catch the liquid that will be drained. Trust us, you don't want that stuff all over the floor.
Find the fill plug on the upper end of the transmission pan and loosen it. IMPORTANT: fluid will come out of this hole once the plug is loosened, make sure you are not under the opening when you do this because you will get dirty. Very dirty.
After all of the fluid from the transmission is drained, replace the fill plug with a new washer and use an oil pump to replace the fluid. Replace the filler bolt and tighten with a torque wrench to ensure it's really on there. No need to remove the entire pan and gasket with a manual transmission.
Clean up any remaining fluid. Boom. You're done.

Now you're all set and have a transmission plan ready to go no matter what kind of car you have! See, that wasn't hard at all.