How to Check Transmission Fluid (Dipstick or No Dipstick)

Pop the hood and look near the back of the engine bay, usually on the driver side, for the transmission. If you see a yellow-handled dipstick clearly marked "TRANS" or "ATF", you have a traditional setup and your job is easy - skip to step 6 and just pull that dipstick.

If instead you see a small black or silver plug where the dipstick tube should be, with no handle to pull, that is a sealed transmission. The plug is a fill port, not a dipstick - the factory expects you to bring the car in. You will use the oil-dipstick workaround starting in step 2.

Here is the trick: your engine oil dipstick has TWO sides. One side is marked with the engine oil min and max - that is the side you normally read. Flip it over and the back is usually blank metal. That blank side is what you will mark for transmission fluid, so the same dipstick now does double duty.

Pull the dipstick, wipe it down with a clean rag, and lay it on a flat surface with the blank side facing up. A workbench or even a piece of cardboard on the driveway works. Do not let the oily side sit on a clean surface or you will spend the next ten minutes wiping black streaks off your garage floor.

Every automatic transmission has a fluid-level-vs-temperature chart that tells you, in millimeters, how far from the tip of the dipstick the fluid should sit at any given temperature. The fluid expands when hot and contracts when cold, so the chart has two ranges: a cold range (around 70F) and a hot range (around 200F operating temp).

To find yours, look up your year/make/model and identify the transmission code (this 2014 Chrysler Town and Country uses the 62TE, for example). Then search "[transmission code] fluid level temperature chart" - the PDF usually pops right up from a service manual or a forum thread. You want the low and high marks for both 70F and 200F.

You will end up with four marks on the blank side of the dipstick: a low and high for cold, and a low and high for hot. On this Chrysler, the chart calls for 4mm and 15mm from the tip at 70F, and 40mm and 54mm at 200F. Use a millimeter tape measure for accuracy. If you only have a standard tape, convert: 4mm is roughly 1/8 inch, 15mm is about 5/8 inch, 40mm is about 1-5/8 inch, and 54mm is about 2-1/8 inch.

Lay the dipstick on a flat board with the tip flush against the edge so your tape has a clean zero. Mark each of the four distances with a Sharpie. Label the cold pair "C" and the hot pair "H" so you do not confuse them at 7am in the driveway.

Sharpie wears off the first time the dipstick goes back into the tube. To make the marks permanent, score right through the center of each Sharpie line with a box cutter or utility knife. Run the blade along a straight edge so the cut is clean and even.

To tell the cold and hot pairs apart at a glance, scratch a little X pattern in between the two cold marks, and leave the area between the two hot marks plain (or vice versa - pick a system and stick with it). The pattern is what your eye will read in low light, not the position alone. From this point on, the dipstick is your forever transmission tool.

The fluid level depends entirely on temperature, so the engine has to be at a known temp before the dipstick reading means anything. For the most accurate hot reading, drive the car for 10 to 15 minutes until the temperature gauge sits at operating temp. For a cold reading, the car needs to have been off for at least a few hours.

Park on level ground - any slope skews the reading. With your foot on the brake, shift slowly through every gear (Park, Reverse, Neutral, Drive, low gears, back to Park) so the fluid fills every passage in the transmission. Leave the engine RUNNING and the lever in Park. This is critical: most automatics are read with the engine running, unlike engine oil which is read with the engine off.

With the engine running and the car in park, push your marked dipstick all the way down the tube until it bottoms out. Hold it there for two seconds so the fluid wets the stick, then pull it straight up without rotating. Read the wet line against your scored marks.

The fluid should sit between your low and high marks for the temperature range you are at - hot pair if the car is warmed up, cold pair if it has been sitting overnight. The fluid itself should be bright translucent red (or pink) and should NOT smell burnt. If it is brown or black, or smells like burnt toast, schedule a full fluid and filter service - the fluid is cooked and continuing to drive on it will damage the clutches.

If the level is low, add the EXACT fluid type your owner's manual specifies (ATF+4 for most Chrysler, Mercon LV for Ford, Dexron VI for GM, and so on) through the fill plug or dipstick tube, a quarter-quart at a time, rechecking between adds. Overfilling is just as bad as underfilling - the fluid foams and the transmission slips.