A3 Transmission Fluid Questions

[Rustygears]

Agreed. These GM automatic transmissions are really manual transmission systems with a series of hydraulic servos and controls to implement the shift process. The working fluid for these systems, in addition to providing basic lubrication for the internal clutches and gear trains, has a significant impact on the timing, thresholds, etc. for decisions regarding when to shift and the orderly coordination of actions involved in a shift. The viscosity of the hydraulic fluid in these systems is a major contributor to their proper operation. My guess is that while GM accepted the Army's use of 10W40 motor oil, for them it is considered marginal at best, providing minimum functionality and service life. Since our rich uncle (Sam) has no problem spending $$ to replace transmissions earlier than what would be considered normal in regular fleet service, they traded that consideration for the operational simplicity of a single grade lubricant for the A3 power train. I'm surprised they didn't put 10W40 in the transfer case and differentials as well for the same reason.

 

[glcaines]

After changing from motor oil to Dexron III in my A3, I decided not to upgrade to Castrol TranSynd. I had flushed 5 gallons of Dexron III through the Allison, and today I flushed another 3 gallons of Dexron III through it. I decided five gallons wasn't enough. I have now listed my five gallons of TranSynd fluid in the classifieds if anyone is interested.

 

[kilness]

Thought I'd revive the thread by stating I finished switching over to dex III. Did the fill and drain method 3 times with driving in between about 40 miles. Replaced both filters on the last drain and fill. What a difference it has made. Seems like the shift points are more consistent. Downshifting is so much smoother than with the motor oil. Of all the things I've done to the truck, this has to be by far the best.

 

[groundog]

I know this thread is about the A-3 but how about the M-939 series trucks--any words of advice/

 

[mktopside]

No idea man, I'd check with your local Allison dealer and see what they think. I think the trans in the 900 series trucks is SIGNIFICANTLY more expensive to replace, so take a few extra minutes to be sure.

 

[73m819]

I know this thread is about the A-3 but how about the M-939 series trucks--any words of advice/

Try here http://www.steelsoldiers.com/5-ton-up/72226-m923a1-transmission-fluid.html

 

[trukhead]

Does the A3 torque converter have a drain plug. Will a drained torque converter have enough internal seal to take up fresh fluid?