[jstubbs]

Seen a few guys mention they have a 2006 Duramax trucks here so I figured I’d give some forewarning about a pretty dumb screw up by GM, I figure if it even saves one guy a few bucks on not having to replace some transmission seals then it’s worth it.

Had a seal start leaking on my Allison transmission in my 2006 2500HD Duramax. Owner’s manual said to use Dexron IV. Decided to just in case see what all the fellas on the Duramax forums say to use. Turns out Allison released a memo stating any 2006 6 speed Allison transmission paired to the Duramax with a serial number before 6310670488 for Indianapolis build and 6320784373 for Baltimore (most Pickups) have seals in the transmission that are NOT very compatible with Dexron IV, and it will eventually cause seals to fail. Those serial numbers also generally coincide with the start of the 2007 classic Duramax trucks, so majority (if not all) 2006 trucks are not recommended by Allison to be using Dexron IV, and should be using either Dexron III or TranSynd (or any TES-295 ATF). Supposedly, running those fluids will both save your seals, possibly extend the life of your trans, and if you’re running a tuner, will also help your trans deal with the extra power a lot better. As well, never allow a trans shop to flush your Allison, supposedly it can seriously damage your transmission, only drain, change the external filter, and fill.

Anyway, I suppose if you have had seals fail on these before, this might explain why. Hope this helps for any of us still clinging on to these old piles of junk. Lol