Mike:

I'm no transaxle expert, but I have drained my transaxle to
replace the standard gear oil with Redline MT 90.

The true experts on this List told me that one can NOT drain
the transaxle completely (without taking it completely
apart).  So don't put any solvents in there!!!   MT90 is
compatible with standard gear oil.  Just drain the gear oil
and mix in your 4 quarts of MT90.  You'll see a market
difference in shifting ability.

I initially put only 3qts of MT90 in the transaxle and the
shifting was very easy. I subsequently learned that a total
of 4qts. can be added. Which I did. However, the shifting is
slightly stiffer, than with 3 qts.

Hope this helps,

- - George Chapman, 91 GL
    Lake Almanor, CA