How to Check Your Transmission Fluid

check transmission fluid — Use a dipstick when checking transmission fluid levels. Velimir Zeland/Shutterstock

Most drivers know that they need to check their oil levels every once in a while and have the oil changed at regular intervals. But what about transmission fluid? Does it need the same level of care and maintenance?

The short answer is no, it does not. Most manufacturers only recommend having the transmission fluid changed if the engine is under "severe use." If you cruise around under normal conditions — not towing large things, or hauling heavy loads, or drag racing at the track every weekend — you probably never need to change your transmission fluid.

In fact, many modern cars have sealed units, meaning you can't check the transmission fluid even if you want to. The fluid level can only be checked and changed by having the car put on a lift in a garage.

But maybe you've been feeling like something is off with your car, like there's a hesitation when the gears shift up or down, even if it's an automatic transmission. Or maybe the engine makes noises when the transmission system shifts gears.

In that case, it's easy and free to check your transmission fluid level. If it's low, there might be leak in the transmission system somewhere, so you'll need to make an appointment with the mechanic.

How to Check Transmission Fluid

Park on a level surface and open your car's hood. Find the transmission fluid dipstick somewhere near the firewall between the engine compartment and the passenger compartment. It looks like the oil dipstick, but it's probably yellow. (Refer to your owner's manual to double-check whether it has a transmission dipstick.) Leave the hood up.

Get into the car and start the engine. Set the parking brake. (Some automatic transmission fluid levels are checked with the engine off. Check your owner's manual.)
Slowly move through the gears — park, reverse, drive and low in an automatic transmission — and return to park.
Carefully remove the transmission dipstick, wipe it with a clean rag and put it back into the dipstick tube.
Remove the transmission dipstick again to see where the transmission fluid level is. The dipstick may have two "full" lines, one for warm fluid and one for cold. If your car has only been running a minute or two, it's cold.
If the fluid level is low, use a funnel to add more transmission fluid.
Replace the transmission dipstick and turn off the car.

To be extra sure you have just enough transmission fluid, you can drive around for a few minutes to bring the engine up to normal operating temperature and check it again. That will be the "warm" level of fluid.

Adding Transmission Fluid

If the transmission fluid level is indeed low, go ahead and add the correct type of transmission fluid for your car. There are different transmission fluids for manual transmissions, automatic transmissions, and continuously variable transmissions, as each has different requirements.

But remember, you're not supposed to have to do anything with the transmission fluid of modern cars for thousands of miles. So if the level is low, there's likely a leak or it's a faulty transmission. But add fluid now to prevent further damage to your whole transmission system and make that appointment at the shop.