Originally Posted By: labdog
Thanks for the replies, I did shoot my question to MR_TRANSYND,who was this Forms most knowledgeable person on Allison Transmissions and who's job it was to certify the fluids for the 5speed and 6speed trannies. He is no longer contributing to this Form but can be reached at the following e-mail and website.
[email protected],
http://www.jglubricantservices.com/
The main issue when your looking for fluid to add to your 5-speed Allison is not putting fluids that will harm the Viton seals. Dex III is what came with the 5-speed but Dex VI is not compatible with the Viton seals. If your only looking for a qt of fluid and end up at
Wal-mart or a parts store unless the container notes that it meets TES-295 and or TES-389 I wouldn't use it. If you have changed over to Amsoil or Transynd or other high quality synthetics that meet and exceed the requirements for Allison's Transmissions than you can add those to your fluid to top it off when changing your spin on filter. This is a GREAT website and Form to get and receive good knowledge and information but let us NOT be-little or criticize those who have the technical and certified knowledge in there areas OF expertise.
This is blown WAY out of proportion, GM dealers have serviced Thousands upon Thousands of Allison 5 speeds with Dexron VI over the years, A LOT of them were under GM powertrain warranty at the time.
There were also thousands of Allison 6 speeds built before the seal change that got filled with Dexron VI at GM assembly plants without issues.
With that being said.....I LOVE Castrol Transynd (TES-295) ATF! I run it in my Allison, 4L80E, & 4L60E. I'm going to try it on the Toyota next......