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How to Check Transmission Fluid

Orange handle of transmission fluid dipstick under a car's hood

Getting in the habit of regular fluid checks on your car saves you a lot of frustration in a short amount of time. You know how to check the oil and eyeball the coolant level in the overflow tank, but what about how to check transmission fluid? This one’s a little more complicated, and it ultimately depends on your vehicle’s age.

Why It’s Important to Check Your Transmission Fluid

Transmission fluid serves two purposes — it keeps your transmission from overheating, which can damage parts, and it acts as a lubricant, which keeps your transmission shifting smoothly. Checking it on a regular basis can let you know if you need to add fluid. If you do, it’s possible you have a leak in a transmission seal, which should be repaired.

Mechanic checking transmission fluidIf You Have an Older Vehicle

If you have an older vehicle — say, 10 years or older, back to the 1970s — you’ll likely spot the transmission fluid dipstick, because it has a bright colored handle with the words “trans fluid” printed on it. And just like with an oil dipstick (usually the red handle with the word “oil” on it), all you do is pull it out, wipe it clean, put it back in, pull it out again and look to see where the fluid reaches on the engraved marker. There are usually three, four or five markings — either dots or vertical lines. The top line indicates it’s full. Anything below the next mark down means you should add fluid until it gets back to the top of the dipstick.

If You Have a Newer Vehicle

In the past few years, many vehicle manufacturers have been moving to “lifetime fill” fluids, and transmission fluid is high on the list. Some newer cars have a sealed transmission fluid system, so you can’t check transmission fluid at all.

Anticipating that move, some manufacturers that haven’t gone to “lifetime fill” are no longer making the transmission fluid dipstick‘s accessibility a priority. Some cars have a dipstick, but it’s so deep in the engine compartment that the owners manual recommends transmission fluid checks be left to the mechanic during a regular service appointment. However, if you still want to DIY and can reach the dipstick without too much effort, this is a project you can take on yourself.

The Downsides of “Lifetime Fill”

Unfortunately, “lifetime fill” doesn’t mean the fluids will last for your lifetime or even your car’s lifetime. Most often, it means the fluids will last for either the manufacturer’s expected life of the vehicle (which varies) or for the lifetime of the warranty (which is far less). If you can’t check your own fluid levels, you can take it to your local NAPA AutoCare, who can take apart the sealed system and do it for you.

The bottom line? If you can check your own transmission fluid level, you should do so once a year. If not, take it to your mechanic or dealer — ideally before your warranty expires, so you’ll be covered in case there’s a problem.

Check out all the transmission fluids available on NAPA Online or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on how to check transmission fluid, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.

Photo courtesy of Flickr.

Mike Hagerty View All

Mike Hagerty is an automotive journalist whose work has been featured on radio, TV, in print and online since 1997. He's the Publisher and Editor of, and contributes car reviews to the Los Altos Town Crier and Previous outlets have included KFBK and in Sacramento, California, the ABC television affiliates and Hearst-Argyle and Emmis radio stations in Phoenix, Arizona; AAA magazines for Arizona, Oklahoma, Northwest Ohio, South Dakota and the Mountain West and

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