I would flush and fill with any of these allison approved TES295 fluids
approved allison fluids
The following is additional information for this fluid group
Transmission fluid does not need to be changed with every filter change; however, when replacing filters you may lose about 10 quarts of fluid during the filter change and will need to refill the transmission to the proper level after the filter change is complete.
When using Allison Lube spec TES 295 fluid, change intervals should be as follows:
Fluid 150,000 miles / 6,000 hours / 48 months; whichever comes first
Main Filter 75,000 miles / 3,000 hours / 36 months; whichever comes first
Lube/Auxiliary Filter 75,000 miles / 3,000 hours / 36 months; whichever comes first
Internal Filter Changed only during transmission overhauls
Initial 10,000 mile change Not required with TES 295 fluids
Also note that effective January 2010, per Allison Service Tip 1099N, Allison no longer authorizes the use of DEXRON® III or IV in any of its transmissions.
– Deep Oil Sump w/o PTO 29qt (27.4)
– Shallow Oil Sump w/o PTO 26qt (24.6)