Checking Automatic Transmission Fluid Level

There is a proper way to do this to determine proper level inside transmission

For accuracy, the transmission fluid level should be checked after the car has been driven at least 15 minutes with the engine running and the gear selector in park. For extreme accuracy measure the temperature of the bottom of the tranmssion pan with a heat gun. ALWAYS use a lint free cloth when wiping the dipstick. A small piece of chamois cloth is preferred. If not available, then wipe with your fingers and clean your finger off on a cloth. Any dirt or lint allowed to enter the transmission can jam the small valves in the valve body and prevent the transmission from shifting properly.

Problem & Solution

Common among these chassis:

W108 W109
W110 W111 W112 Sedan
W111 W112 Coupe

If you are filling or checking the level when the transmission is cold then only fill to half-way between the low and high marks on the dipstick.  When adding fluid let the engine run for a few minutes and then re-check level.  If you don't do this you can get a false reading on the stick. Drive the car and when hot, recheck level and top off if necessary. REMEMBER the amount required between the low and high marks is not a quart!  It is much less, so add about a quarter of half a cup at a time and then recheck with the dipstick.

Do not drive with the transmission overfilled. If you accidentally add to much, you will have to drain the extra out through the drain on the transmission pan or use a fluid extractor placed down in the fill tube. If you have an older style transmission that does not have a drain plug on the pan, you can loosen the banjo bolt fitting at the bottom of the fill tube (where it connects to the pan) to drain out excess fluid. 

Kent has develped a unique tool for extracting excess fluid from your tranmission as well as a kit to measure and inspect the fluid inside the "sealed for life" transmissions.