Hello

, you do not indicate the year, but in GM you do not have "rod" to measure the oil you must search in the box. There is a filling and emptying cap ... as in the mechanical boxes. To measure the level you must extract the cap that is to the middle of the box, if oil comes out the level is ok, if you should not add. If the oil is murky, with the smell of burnt ATF, do not hesitate to change it, the oil is the life of any velocity box ... particularly in automatic.