It will read high after sitting for awhile. If I am not mistaken the 5 mm below the low mark or something is where the level should be after it is started with the tranny cold. You need to run it out on the interstate (75+ mph) for at least 20 minutes to get it good and hot then check/set the level. The tranny will start acting up when the level gets too low (below the lower mark). I want to say that I seem to remember that it will start slipping during gear changes when it is too low but not sure. It has been awhile since I rode in one that was way low and that was after I had changed it and was in the process of getting the level back where it needed to be. Personally, I find getting the level where it needs to be one of the more pia type maintenance activities on these cars.