I had my Allison 3000 transmission oil changed to Trans Syn synthetic fluid at 34,911 on 2/12/15. I have now just under 50,000 miles and my question is should I have the transmission fluid changed again? I understand at the fluid change at 34,000 that the oil in the torque converter was not changed so this change would add too the impurity of the synthetic fluid. I also wondered if I waited too long to make the second synthetic change? my transmission seems to perform perfectly. Any thoughts or ideas? The diesel engine is the Cat C7. Thank-you

Have the fluid tested by JG Labs. I have it done once a year, their report will tell you everything you need to know.http://www.jglubricantservices.com/

Allison is still showing every 48 months for a fluid change. I think you have past that mark.On ours when its due a fluid change I replace the filters so don't have to open it up again for a while. I can feel a smoother shift when I do ours. Even though I was smooth before it even better to me when its change completely. We have the 4000.

After the first change to Transynd, according to Allison, you stay with the service interval for Dexron.After the second change with Transynd, you go to the Transynd service interval.Very interested in learning more about Allison's new ATF TES 668 and in what way it is different than the Transynd we have "known and loved" all these years.

Allison 3000 transmission | Good Sam Community

Lwiddis
Explorer II
Jun 05, 2021
What does Allison recommend?
Ivylog
Explorer III
Jun 05, 2021
No.
Blaster_Man
Explorer
Jun 06, 2021
Have the fluid tested by JG Labs. I have it done once a year, their report will tell you everything you need to know.

http://www.jglubricantservices.com/
MountainAir05
Explorer II
Jun 06, 2021
Allison is still showing every 48 months for a fluid change. I think you have past that mark.

On ours when its due a fluid change I replace the filters so don't have to open it up again for a while. I can feel a smoother shift when I do ours. Even though I was smooth before it even better to me when its change completely. We have the 4000.
wolfe10
Explorer
Jun 06, 2021
After the first change to Transynd, according to Allison, you stay with the service interval for Dexron.

After the second change with Transynd, you go to the Transynd service interval.

Very interested in learning more about Allison's new ATF TES 668 and in what way it is different than the Transynd we have "known and loved" all these years.
Blaster_Man
Explorer
Jun 07, 2021
As long as it tests good, no change is required...per Allison.
wolfe10
Explorer
Jun 07, 2021
Guess I am conservative when it comes to fluid changes-- much cheaper than the machinery they lubricate.

6 1/2 years-- I would change it.
udidwht
Explorer
Jun 07, 2021
No combustion process going on in a transmission so a time based interval would not apply. Trans syn fluid can live 100K easily.
wolfe10
Explorer
Jun 07, 2021
Allison's new generation fluid Transynd TES 668.

It supersedes Transynd TES 295 and is backwards compatible.

Allison video:

https://www.youtube.com/watch?v=T3XU2BEHBV8

Stick with the change interval based on your current fluid's recommended change interval which is affected by Allison's duty rating. Allison classifies any transmission with a retarder as "severe duty".

And, when you do change, go to the improved TES 668. I visited with Tom Johnson who helped develop Transynd TES 295 and he highly recommends going to the TES 668 at the next change interval as the additive package is even improved over the TES 295. Basically, there have been strides in chemistry over the last decade! Take advantage of them.
MountainAir05
Explorer II
Jun 07, 2021
Sorry for the rant: