[Archived]

Depends. Allison has a schedule for each type of transmission on their web site based on the fluid used, type of transmission, and if it is used for what they consider hevey duty use, such as retarder equipped transmissions or towing a trailer.

For the 6 speed transmissions with Transynd and based on the miles most of us drive 4 years is a common interval for fluid and filters.

[Archived]

When you use Transynd, Allison recommends service every 5 years.

[Andre]

I can find no Allison approved interval that exceeds 48 months. Transynd is very expensive but far cheaper than a transmission.

http://www.allisontransmission.com/docs/default-source/service-documents/st1099s.pdf?sfvrsn=2

[Jim]

Jon, see page 17/28 on your link for some 60 month intervals.

[Pat & Jan]

Aren’t those filter change intervals? Or am I misreading it?

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2025 Marathon H3 / 4th Prevost
21 Ram 1500 EcoDiesel 4x4

[Archived]

Looked again. The 60 month interval is for both fluid and filter IF your using Allison spec TES 295.