Oil Pressure and type of Tranny Fluid??

[jjonesak]

I have a 79 international school bus with a dt 466 and an allison auto tranny and i have a couple questions!
First what is the normal oil pressure when motor is first started, warmed up at idle and at highway speed(50-55),second what type of tranny fluid do the allison trannys take?Any info would be much apprecaited! thanks alot.

Josh

[the_experience03]

Thje general rule is 10 psi for every 1000 rpm so I think you're just fine there.

As for the tranny fluid...I have the manual for my AT545 and it gives a whole bunch of acceptable fluids given the temperature. Your best bet? Some Dexron III that has an Allison C4 or other rating on it. Synthetic runs the change interval out from 25,000 miles to 100,000 miles. The Allison branded synthetic is called TranSynd.

Allison's website is pretty good and full if information, save for being somewhat difficult to navigate at first.


http://www.allisontransmission.com

[jjonesak]

AWsome thanks for the info!!

Josh

[jjonesak]

WOW so they can take a whole lot of diffrent ones looks like pretty much any dextron 3 will work!? just look for the C4 allison thing on the bottle!?

[the_experience03]

Go to the Allison site and see what the recommend. I don't have my manual here to give you specifics, but I remember a couple different weights of motor oil, etc were acceptable given the correct temperature outside and proper warm up of the transmission.

[Elliot Naess]

As I understand it, the motor oil that was approved for use in the Allison AT545 transmission was a NON-DETERGENT motor oil. This is critical, as a "real" motor oil would be far to slippery. After all, an automatic transmission functions by friction clutches. The reason for using the C4 non-detergent motor oil in the AT545 was to reduce slippage in the non-lockup torque converter.
Last I heard, this practice has gone out of fashion as there were problems with the C4 oil also.
With a DT466, you probably have an MT643 tranny, which has lockup.
Dexron or TranSynd, from all I have heard so far. Change often, including the filter, and don't let it get too hot.

[budman56]

Originally Posted by Elliot Naess

As I understand it, the motor oil that was approved for use in the Allison AT545 transmission was a NON-DETERGENT motor oil. This is critical, as a "real" motor oil would be far to slippery. After all, an automatic transmission functions by friction clutches. The reason for using the C4 non-detergent motor oil in the AT545 was to reduce slippage in the non-lockup torque converter.
Last I heard, this practice has gone out of fashion as there were problems with the C4 oil also.
With a DT466, you probably have an MT643 tranny, which has lockup.
Dexron or TranSynd, from all I have heard so far. Change often, including the filter, and don't let it get too hot.

Just checking with every one here I am new to these transmission and I have a AT 5454 with roughly 54,000 miles on it and I want to change the oil and want to make sure I am using the correct stuff (see attached photo of what I believe is the correct oil) Please confirm and thank you for all your help.

[Booyah45828]

That looks like it will work, being that it's allison c4 spec. But I've never heard of triax before and would be leery of using them.