How to Check Transmission Fluid Level: Dipstick or Sealed

The usual routine of warming it up, pulling the stick, wiping it and reading it only works on cars that have a transmission dipstick. Many newer automatics don't.

Ram's own manual says its eight-speed has no dipstick because routine level checks aren't required. So the first job is finding out which kind you have.

Where is the transmission dipstick?

On cars that have one, it sits toward the back of the engine bay. That's near the firewall, the panel between engine and cabin, on a front-wheel-drive car, or along the transmission tunnel on a rear-wheel-drive one.

Open the hood with the engine cold and look for a second dipstick besides the engine oil one. The engine oil dipstick usually sits nearer the front.

Its handle is often marked with a gear symbol or the letters ATF, short for automatic transmission fluid. Honda's manual for an older Accord calls its dipstick the yellow loop, and Ram's pictures a long wire ending in a lock cap.

One Ram recall involves this very tube. On the 2020–2023 Ram 2500 and 2020–2022 Ram 3500, the dealer replaces the dipstick and vent under recall 22V-835, because fluid can leak from the tube and start a fire. Check the VIN for it before you pull the stick.

If you find one, you can do the check below yourself. If there's nothing there, an automatic is most likely sealed, as your manual will say, and a shop checks it without a dipstick, at a plug underneath the car.

Some cars have a dipstick tube that has been capped, or a filler that needs a special tool to open, and those are sealed in practice. A manual transmission has no dipstick either, and its level check is in the owner's manual. The photo marks the engine oil dipstick and the band where a transmission dipstick would stand, which this car doesn't have.

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How do you check transmission fluid?

Warm it up, then read the stick the way your manual says, if the car has one. Most mistakes come from reading it cold or out of gear, so get the fluid hot and the selector right first.

The temperatures below come from the 2022 Ram 2500 and 3500 owner's manual. To check transmission fluid level with a dipstick, go in order, because the order is the procedure:

1. Get it properly hot. Drive it first, unless your manual says otherwise. Ram wants the fluid at 158–176°F (70–80°C), which normally takes at least 15 miles of driving.
2. Park level and let it idle. On level ground, because every mark on the stick assumes the transmission is sitting flat, with the engine running, unless your manual says off.
3. Parking brake on, foot on the brake. Both, before anything is moved, because the next step puts the transmission into gear.
4. Through every gear, ending in Park. Move the selector into each position in turn and give the transmission time to engage in each one.
5. Pull it, wipe it, seat it. Keeping hands and clothes clear of the belts and fan, draw the dipstick out, wipe it clean, then push it back until it seats.
6. Pull it again and read both sides. The level belongs between the hot marks, and it only counts if both sides show fluid.
7. Seat it. Push the dipstick fully home, then check for leaks and release the parking brake.

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What happens if you overfill it?

Over-filled fluid can foam and vent out, so it isn't a mistake you can leave. A GM service bulletin says it can spill from the vent tube or make the pump draw in bubbles instead of fluid.

Some dipsticks also carry two sets of marks. On the Ram stick, the upper "HOT" pair is the real check, and Ram's cold marks are for setting the level after a fluid change, at 60–70°F (16–21°C).

Do you check transmission fluid hot or cold?

Check it hot on a dipstick car, after the drive in step 1, unless your manual says otherwise. Ram warns that below 50°F (10°C) the fluid may not register on the stick at all.

Reading it cold is the common mistake. A correctly filled transmission can look empty on a winter morning, and topping it off then overfills it.

Sealed transmissions are checked cooler, and every maker picks its own window. GM's bulletin says a level set too cold ends up over-filled, and one set too hot ends up under-filled.

Each of those windows is cooler than a dipstick check, and each maker's figure is in the documents below. A sealed transmission warmed like a dipstick one would be too hot to read, so the check belongs to a shop with a scan tool.

Do you check transmission fluid with the car running?

On most automatics, yes, which is the opposite of engine oil. Ram has you idle for sixty seconds and leave it running for the rest of the check, and the Stellantis procedure keeps the engine running from start to finish.

GM's bulletin says why it matters on a sealed unit: its caution says the engine must be running when the check plug comes out, or so much fluid drains that the transmission ends up under-filled. Never get under a car held only by a jack, as Ram's and Honda's manuals warn.

Honda is the exception worth knowing. Its manual for an older Accord says to shut the engine off, then wait 60–90 seconds before pulling the dipstick, so your own manual wins over any general rule, this page included.

The selector position differs too. Ram and GM end the check in Park, while Hyundai's eight-speed is checked in Neutral.

Is your transmission fluid low, full or overfilled?

Between the hot marks is full, below them is low and above them is overfilled, once it was read the way your manual says. Each of the three has its own next step.

1. It reads between the hot marks

Nothing to do but note where it sits and look at its color and smell, so you have something to compare against next time. A stick that read correctly last month and lower today tells you more than any single reading.

Check it again if you notice a leak or the transmission starts acting up. Those are the two reasons Ram gives for having the level checked.

2. It reads low

Add a little of the specified fluid, wait two minutes, and read again, never on a cold reading. Before any long drive, find out why it was low: Ram says the wrong level can cause severe damage, and our leak guide below covers where the fluid usually goes.

3. It reads high

Recheck once the fluid is fully hot, since the marks assume it. If it's still high, have the extra drained: GM's own fix for over-filled units was to drain the excess at the check plug.

Can you just add transmission fluid?

On a car with a dipstick, yes, through the tube or fill plug, and not at all from above on a car that doesn't. There's no set amount, because the right amount is whatever brings the level back to the mark.

When you add transmission fluid, watch three things:

• How much. A little at a time, through a funnel with a long neck. Ram says to wait at least two minutes for it to drain down before rechecking, and not to overfill.
• Engine state. The same as for the reading, as your manual sets it.
• Not while it's cold. Ram says to add nothing until the fluid has warmed up, because a cold one can read empty.

Where does transmission fluid go in?

On Ram's six-speed truck, where to put transmission fluid is the dipstick tube itself. Honda's older Accord manual has you remove a separate fill plug instead, and on a sealed transmission the way in is a plug on the case, reached from underneath.

Some sealed eight-speeds have a second plug just for reading the level. Adding it there isn't a driveway job: it takes a fluid pump at the fill plug.

Under the hood, the cap or handle may name the fluid too, such as Mazda's "A7" or "FZ". Use only the fluid the manual names, because transmission fluids aren't interchangeable, and the makers' documents are just as blunt.

What if your car has no dipstick?

A shop reads the level on a lift, with a scan tool, at a plug on the case, and you pay for that time. Sealed doesn't mean the fluid never needs looking at, but the reading only works under conditions you can't produce on a driveway.

On the ZF eight-speed in many BMW and Stellantis cars, the level is right when fluid only drips from the fill hole. BMW says the level can only be checked with a named test plan on its diagnostic system.

Our guide to checking without a dipstick walks through each maker's full procedure. If your car has a dipstick, the steps above are all you need.

What does a transmission fluid check cost?

Nothing on a dipstick car, and about $30–$42 in labor on a sealed one, from the 0.3 hours GM's bulletin allows for the check. A dipstick car needs only a drive, a clean rag and the 7 steps.

On a sealed car, ask for the check while the car is already up for other work, so it costs no extra trip. Other makes may book it differently, and labor rates vary by shop, so hold a quote against that range.

How often should you check transmission fluid?

Now and then on a dipstick car, because it's free and it's the cheapest early warning you have. On a sealed car, don't put it on a schedule: Ram's manual says routine checks aren't required on its eight-speed.

Check a sealed car when something has actually happened: a leak, a change in how it shifts, or a repair that opened the transmission. Ram names leakage or a malfunction as the reasons, because driving with the wrong level can cause severe damage.

The signs of a low level overlap with the signs of a failing transmission, which is exactly why the level gets checked first. Our low transmission fluid symptoms guide works through them one by one.

If yours keeps dropping, the level is a symptom rather than the problem, and our guide to transmission fluid leak repair cost covers where it goes. And if a shop offers to change the fluid while you're there, whether a transmission flush is necessary is a separate question.

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Common questions

Asked most often

Is one quart of transmission fluid enough?

There's no set top-off amount, because the right amount is whatever brings the level back between the marks. Add a little, wait two minutes and read again, rather than pouring in a whole quart at once.

Do you leave the car running when adding transmission fluid?

On a car whose check is done running, yes: Ram's engine stays on for the whole procedure, adding included. On a car whose manual says engine off, like the older Honda, add it with the engine off.

Does "sealed for life" mean the fluid never needs changing?

Ram says the factory fluid in its eight-speed lasts the life of the vehicle under normal use. It still calls for a change if the fluid gets contaminated, with water for example, or the transmission is taken apart.

Prices are for the US market and vary by region, vehicle and shop rate. Procedures differ between manufacturers, so where your owner's manual disagrees with anything here, follow the manual. This article is general information, not advice about your specific vehicle. See the disclaimer.