Automatic Transmission Maintenance

Make sure the transmission is in Park and the safety brake is fully engaged before looking under the hood. Then check the ATF level the same way you examine your engine's oil level. Remove the dipstick, clean it with a cloth or paper towel, and then re-insert, making sure the stick is seated completely into its tube. Next, remove the dipstick, and look at the fluid level on the stick to see how close it comes to the "FULL" mark.

ATF Specifics
Despite the similarity with an oil dipstick, there are a couple of other significant differences between oil and ATF checks. First, the ATF dipstick is much more flexible and often longer than the oil level stick, making it more difficult to thread into its tube. Just exercise a bit of patience; a well-lighted area should make the job easier.


Second, the ATF fluid level on the dipstick is a more transparent than engine oil, making it harder to read. The easiest way to determine the level is to place the stick against a clean, white cloth. The ATF level should be between the ADD mark and the FULL mark on the dipstick. The difference between the two marks is roughly one quart of fluid. If the level is at or below the ADD mark, add a quart and recheck the level after a minute or two. If the fluid is dark or smells burnt, check with your mechanic about having the transmission flushed and refilled.


To add fluid, use a funnel inserted in the dipstick tube (yet another difference from engine oil, which has a separate filler hole and cap). Pour slowly, adding just enough to bring the level up to FULL. This is one of those cases where too much is inadvisable as the fluid can become aerated and lose its lubricating ability.

ATF Types
Choosing the correct ATF is more complicated than engine oil where the decision is based on recommended viscosity. So, back to your owner's manual. As a clue, late-model GM automatics requires Dexron-IIE and Dexron III; Chryslers require Mopar ATF-Plus; most late-model Fords use Mercon; Ford vehicles from the early '60s through '80s used Type F which can't be substituted for the Mercon in late-model Fords. Dexron IIE can be substituted for Mercon and Mopar ATF-Plus.