Allison Transmission Fluid Research

[Barron]

I delved into the Allison manuals today and came up with some basic info for all Allison Automatic Tranny users.

The earlier 1990's Allison manuals say that Dexron III is suitable for "On Highway"
The suggestion is made for C-4 fluid for "Off Highway"
C-4 #30 Weight is suggested for "Severe Duty" in ambient temps above 95F
Both the DEX III and C-4 carry a 12 month oil change recommendation with filters.

A Volvo truck manual for the MT600 series transmission includes the use of:
#10wt motor oil
#20wt motor oil
#0W20 motor oil
#30wt motor oil
#15-40 Motor oil

The latest Allison bulletins no longer acknowledge Dex III or C-4 since the new full synthetic heavy duty TES-295 oil spec was intoduced.

The Achilles heel of these transmissions is apparently Anti-freeze, or Ethylene Glycol. It will wreck the clutches and the whole tranny. Contamination comes from a faulty heat exchanger leaking into the trans fluid.

Bottom line is these Transmissions will eat just about anything as far as oil is concerned. Allison calls out a "Double Flush" for a fluid type change. Drain and change the filters, fill with oil, drive for 30 minutes, drain, and refill.

The main thing is to use an oil suitable to your useage, change the filters and keep good clean oil in it.
Hope that helps..

 

[engineer233]

The local National Guard depot near me said they use 15-40 in their 939 series trucks. How can I tell what is in my truck ?

 

[Beerslayer]

The local National Guard depot near me said they use 15-40 in their 939 series trucks. How can I tell what is in my truck ?

Probably the best thing you can do is change it. Unless you have a service record of the last change. Once you change it, you will know.

I think I am going to go with 15-40, as it will work in the motor too.

 

[Gunnermac]

There a number of threads on this subject. Run a search and you will find a great deal of info.

 

[Stalwart]

Using 15w-40 motor oil was "approved" as a request of the military so they didn't have to stock another oil. Allison didn't really recommend this change but said they could use it. The Allisons in the HEMTTs suffered horribly from this change of oil, the transmissions simply didn't last. They would have been better off stocking the appropriate hydraulic transmission fluid for the transmissions when serviced on base and in the field, with permission to use 15W-40 on an emergency or dire need basis. Alas, if you want your transmission to live to its designed service life, get that motor oil out of it and use the latest "approved" oil by Allison for your transmission.

 

[cranetruck]

FWIW, I use "Tractor hydraulic fluid" in my 1969 Allison TX200-6 (similar to MT31).

 

[Rustygears]

Ditto.

I use Napa hydraulic and transmission oil in my A3 which has an Allison tranny. The Napa oil carries the Alilison C4 rating and a bunch of other certs for other mfgs. After switching from 15W40, it shifts smoother and runs lots cooler. Others have posted similar experiences. Others claimed changing to dex III caused their 4th gear clutches to wear and fail, though knowledgable parties attributed it to coincidence. The temperature drop is dramatic and that is a good thing!

 

[BKubu]

I just took one of my M939 series trucks to Allison and I specified DEXIII because I don't want to pay for the synthetic, which I am sure is better, but is not needed for my use. I drive my trucks quite a bit, but I don't work them. They get used gently, which I would bet is the same for most of us hobbyists.

 

[Buttweet]

Just changed fluid in my M923 tranny. Took pan off and changed internal filter. Was messy job. Took awhile. Gasket was troublesome. Used sewing thread to tie gasket to pan in a few places, but kept thread ends outside pan. One attachment bolt twisted off. May have some seepage. Refilled with NAPA Dexron III, $68 for first flush. Fluid that came out was extremely clear and clean, but you never know. Think it was the 10wt with 3500 mi on it.
Still have fluid in my hair.
Thanks
JR

 

[rorybellows]

the correct oil type is imperative, auto or manual. i recently changed the mtf in my nissan, and can really tell the difference in shifting. when the fluid is cold its a pain to shift, but when it warms up, it shifts fine. just sayin. i know these trannies in 939 series take motor oil, and as stalwart said its just so uncle sam didnt have to stock another, more expensive fluid. but in the end, it wouldve been to the gubmints benefit to use the right stuff. just like using jp-8. our trucks never hauled anything heavy, except when we pushed north into iraq. some got gun boxes, but not nearly close to the weight rating of anything on the truck. i did however "killed" a nhc 250 towing an uparmored fmtv tractor back from st mikes one day. did a post check and the tranny fluid looked and smelled fine. i gotta tell ya, the tranny going south was more of a worry to me than the motor at the time

 

[FUBIJAR]

TES295 takes the place of the following-

Allison TES-389 (AA-32332007)
- Municipal fleets

- Vans
- Buses, school buses, coaches
- Emergency vehicles
- Commercial vehicles and trucks
- Motor homes

- On/off highway vehicles

- Heavy duty pickup trucks

- Former Dextron
® III applications
- Former Ford Mercon
® applications
- Ford Mercon
® V (M5060501)
- Voith
- ZF TE-ML14B, 16L, 17C
- Allison C-4
- MAN 339 Type F


Compatible with most other automotive transmission fluids and seals -
When changing to PrimaTech

TES295 it is recommended that the transmission system is appropriately drained and flushed in order to
obtain all of the performance benefits that changing to this fluid will provide. However, PrimaTech TES295 is
compatible with most other transmission fluids and seals