RE: average life of MBZ transmission is only 100k miles??
Buy some Trans-x and cheap tranny fluid.
Drain fluid(don't know if the torque converter
has the same drain plug as the w123 does, if yes, remove plug to drain TC),pour in trans-x according to bottle and fill rest with tranny fluid.
Drain after 100 miles.
You might have to repeat the above once or
If OK, proceed with next step.
Replace filter, add Trans-x(according to
directions)and fill with mobil 1 synthetic
PS: Probably the reason why they don't
last longer is because of the suggested
service interval(I don't know what it is
but it would not surprice me if it is 100K)