Here's some interesting info from twowheelers.tripod.com:
Subject: Tomos Transmission Lube
The Tomos A35 operator's manual specifies Type A Suffix A Automatic
Transmission Fluid as the correct oil for the automatic gearbox.
Dexron, Dexron II, Dexron IIE and Dexron III are the later versions of
this basic ATF lubricant family. These newer type fluids are superior
for automotive transmissions which have pressure pumps and fluid torque
converters and different types of clutches...However, I would suppose
that the unique design of the Tomos automatic gearbox with drum type
centrifugal clutches and no pressure pump or torque converter would
suggest that the older specification Type A Suffix A fluid which this
transmission was designed around, would be more suitable for long
clutch life and proper gear lubrication! All types of fluid are readily
available in Europe so I would assume that the Tomos engineers have a
reason for recommending the Type A Suffix A product rather than a later
Dexron specification product.
Here in the United States, the Dexron III product has become the
standard and it is almost impossible to find the Type A Suffix A
product!
After an exhaustive search for Type A Suffix A product in the U.S., I
have found only one company which distributes ATF Type A Suffix A
product. For those Tomos owners and dealers in the U.S. who would wish
to purchase this product, here is the information:
Coastal Unilube, Inc.
P.O. Box 2048
West Memphis, Arkansas 72303
Product Part # 11501
Type A Suffix A Automatic Transmission Fluid
The Dexron III fluid has a higher viscosity at 100 degrees C. but
at much cooler normal operating temperature of the fluid in the Tomos
application, I suspect that the Type A fluid is much more viscous
(thicker) than the Dexron III. My perception (which may not be
accurate) is that the whine of the straight cut gears is less with Type
A than it is with Dexron as I have experimented with both...Incidentally
my new machine is a Type A35SL Sprint which is the "2000 model year"
...the label on the frame head says 01/00 (January 2000)......It was
filled from the factory with Type A which I was able to identify by
viscosity and odor which is distinctly different from the Dexron fluids!
Will Dickerson, Lancaster, Ohio
Official reply from Tomos Service Department is as follows:
We recommend any oil for use in the A5 engine's transmission as long as
it's intended for use in automatic transmission application.