Don't know about the MT-90, but MTL has friction modifiers added to the synthetic oil base to help shifting. I have MTL in my 1992 Saab 900. I'll be turning over 200,000 miles very soon. MTL made a big difference in shifting compared to the OEM oil. Probably should change it one of these days.

-d

At 09:18 AM 9/23/2002 -0700, you wrote:
>why mtl over mt-90. I thouhg it had to do with the inner working and
>hidden mechanisms of the tranny. According to darrel christensen of AA
>transaxles, you want mt-90 due to the angle of the spinning gears
>(verticle or horizontal). I run mt-90 in my syncro tranny and front diff.
>
>matthew
>86 syncro westy i4
>
>On Mon, 23 Sep 2002, Bob Stevens wrote:
>
>> I'm switching my '87 Syncro Westy manual also Pat, to MTL. That has been
>> recommended by several people to me from this list.
>