How do you check the transmission fluid level on the newer "lifetime fill" transmissions? My 2001 S500 had a slight leak from the pan gasket and I would like to add some fluid if possible.

Special tool 140 589 15 21 00 is a dipstick just for checking ATF level on the 722.6 transmission. Maybe there's a local transmission shop that has one. If so they probably wouldn't mind checking the level for you. Just make sure to use the correct fluid if it needs topping off.

Thanks for the response. Do you know where does the dipstick go and where do you add fluid?