Here's a few specs found on tractorbynet.com. Take them for what they are worth, or not worth.
My dealer gave me a couple pages of literature on UDT, Super UDT and AW Hydraulic. He uses UDT and recommends it, says some people feel the need for Super UDT, and that the AW Hydraulic 46 is something new to him.
The sheets make it hard to make direct comparisons because of properties being listed at different temperatures for the different products. I'll try to post the info:
Both UDT and Super UDT are called multipurpose all-weather tractor hydraulic fluids. They are listed for use in hydraulic, final drive, transmission, differential, and wet brake applications.
Both are "recommended where the following are specified:"
Allis Chalmers - PF821, Part #'s 9003088, 9003089, 9003090, 9003091
Allison - C-3 & C-4
Caterpillar - TO-2
J.I. Case / David Brown - MS-1210, MS-12006, JC143, JIC144, JIC145
John Deere - 303, J14C, J20A, J20C
Ford Select-O-Speed - M2C41B, M2C48B, M2C53A, M2C86A, and M2C134D, C, B, & A
International Harvester - Hy-Tran Fluid, Specification B-6 and superseded B-5
Kubota - Hydraulic / Transmission Fluid
Massey-Ferguson - M-1110, M-1127A&B, M1129A, M1135, Permatran III
Steiger - Hydraulic / Transmission Fluid
Versatile - Gear / Hydraulic / Wet Brake Oil
White Universal Hydraulic / Transmission Fluid - Part #'s Q-1776, 30-310-5695, 30-310-5717
White Oliver - Typ5 (sic?)
Only the Super has the following notes:
*Reduced warmup time for operation in cold weather
*Improves efficiency in synchro and glide shift transmissions
*Fully intercahngeable with standard UDT fluids
*Provides high performance protection even at high operating temperatures
*Meets Kubota's stringent Specifications
Properties listed for UDT are:
Gravity, degree API 29.5
Viscosity @ -30°C, cP 18,300
Viscosity @100°C, cSt 9.5
Viscosity @ 40°C, cSt 60.0
Viscosity Index 140
Pour Point, C° max -35
Zinc, % wt. 0.12
For Super UDT:
Specific Gravity @-15.6° .0877
Viscosity @ 25°C, cSt 84
Viscosity @ 100°C, cSt 9.00
Viscosity @ 40°C, cSt 45
Pour Point, C° max -46
Zinc % wt. 0.17