Tranny Leaking in '89 200T

[lcn@mitre.org (Lawrence Newman)]

My 1989 200T (auto) is leaking oil through an output shaft seal.  I just
bought the car this year and the first thing I had done was to have the
transmission oil and filter changed.  Within a couple of months after that,
I noticed oil leaking and checked the oil level.  It was about 1.25 inches
above the full mark.  I spoke to the mechanic about this and he said the
two weren't related.  At one time in the dim past, I learned (not from
experience) that the consequence of too much oil in the transmission was
blown seals.  The rationale was that increasing oil beyond the fill mark
increases internal pressure and tends to force oil past the seals.

The question is: is this true?  Does overfilling the auto. transmission by
this amount put the seals at risk?   If it does, is there an authoritative
source for this knowledge?

Thanks,

Larry Newman