Gmc 2500hd Duramax Allison Trans Fluid Change?

[Dave1]

I have a 2006 GMC 2500HD 4WD Duramax diesel with the Allison HD auto transmission. I have heard varying opinions about changing the transmission fluid and how to change it. General opinions I have read and heard seems to be to; drain the pan only, change filter, and refill with appropriate amount of new Dexron VI or Transyn fluid. This method drains only the amount of fluid in the pan and replaces only a portion of the total fluid capacity. I suppose this would help to freshen up the fluid, but it does not replace all of the fluid at any one time. I am wondering is this good enough and how often should this be done?

 

Thanks, Dave

[98silvz71]

I have a 2006 GMC 2500HD 4WD Duramax diesel with the Allison HD auto transmission. I have heard varying opinions about changing the transmission fluid and how to change it. General opinions I have read and heard seems to be to; drain the pan only, change filter, and refill with appropriate amount of new Dexron VI or Transyn fluid. This method drains only the amount of fluid in the pan and replaces only a portion of the total fluid capacity. I suppose this would help to freshen up the fluid, but it does not replace all of the fluid at any one time. I am wondering is this good enough and how often should this be done?

 

Thanks, Dave

 

Well first, do not put Dexron VI in the 2007 Classic and older Allisons. If you go on Allison's website they say not to on the older transmissions. I would stick with the Transynd. I don't have an answer for you. According to the manual, GM recommends to change it every 50,000 or 25,000 severe duty. However if you read the Transynd info, it says it is good for 150,000 miles severe duty. I hav seen some guys that drain the pan, flush the cooler lines and pump fluid in with the pan off til new fluid pours out to try and replace all the fluid in the tranny. But I myself would probably drain the pan and pump new fluid in til fresh fluid comes out. As long as the there are new filters installed, they should pick up any leftover dirt in the old fluid and with all the new fluid it should even out ok.

 

Here is info about the fluid.

 

Q. Automatic Transmission Fluid (ATF) - Can I use synthetic fluid?

A. Any fluid that meets DEXRON III requirements is suitable for use in the Allison 1000 Series™. Always verify that the container reads DEXRON III, regardless of whether it is mineral-based or synthetic.

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Q. Automatic Transmission Fluid (ATF) - Can I use TranSynd fluid?

A. TranSynd is a fully synthetic transmission fluid available from Allison Distributors/Dealers or at GM dealers. TranSynd is a licensed DEXRON III product and has been extensively tested by Allison Engineering in a broad range of Allison products. While TranSynd was developed mainly to meet the harsh operating conditions of heavy-duty transmissions in severe operating conditions like transit buses, its benefits translate to the pickup truck market.

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Q. Automatic Transmission Fluid (ATF) - What type of Transmission fluid can I use?

A. Transmission fluids licensed by General Motors to use the trademark DEXRON III are required in the Allison 1000 Series™ transmission.

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