I had mine changed, fluid and filter at around 30K, and will again at
the 60K service. I believe the manual (at least the one the dealers
use) recommends it first time at 60K.
Way back I had some slippage problems traced to "code 00641-006", but
chose not/not to crack the case and trace it further since it went away
after the service.
It has been fine since. God, I wish I hadn't have said that...
Scott in Des Moines
P.S. ...and yes, mine "clunks" at light throttle between 2nd and 3rd,
and kind of "lurches" into 4th, but I have grown to accept these as
peccadilloes of the tranny setup I have with my GL. In all, it has
been the lowest cost per mile vehicle to maintain I have ever owned.
Shoot, there I go again.