939a2 transmission OTA cooler and proffered 10w oil.

Its time to change my trans oil and filters in my 925a2. It has been running fine for the past 10 years. It came with motor oil. I'm not sure if its 10w or 15w-40 but I think I'm going to put 10w in it.

I am not a big fan of the oil to oil cooler for the trans. I dont think they cool very well and have the potential as they age to leak and ruin the transmission. Has anyone put an oil to air cooler in? What did you use? Did you bypass the OTO cooler?

I have not seen many threads on specifically what brands of 10w oil to use. They are hard to find locally. My options right now seem to be Napa TO-4 SAE 10W Transmission drive train and hydraulic oil. Shell Rotella HD tractor transmission and hydraulic oil. That one might be a 10w-30 though. I have seen no mention of either being used on here. Or I can mail order some Mobiltrans HD 10w but that is really more then I want to spend. Only 1 person I can find has used the Mobiltrans. I normally shy away from Valvoline because every time I look into using them the manufacturers tell me its less then preferred. An example is my Eaton trutracs. What brand of 10w oils are we using and how do we like them so far?

My understanding to change the trans fluid is as follows. I should drain it then refill it. Then drive it until it is hot and drain it and fill it one last time. Do I change the filters on the first or 2nd drains?

Please correct me if I am wrong here. I can use the same 10w oil in the trans as the power steering and the hydraulic tank for my winch.

Sorry for all the questions. I have read posts on this stuff for a year or more and I cant put the work off any longer.

If you are using motor oil to replace motor oil then you can drain the pan and refill it. If you want to cycle it thru then that is fine and drain it again. Won't hurt anything.

10w oil from Napa is fine.

The Heat exchanger is designed to keep the transmission at the same temperature as the engine and let one radiator do all the work. It also is there for faster warmups in the colder places.

Swampdonkey just did a stand alone air oil cooler with its own fan. He also added valves so he could bypass the heat exchanger in the summer time and use it in the winter time. It is a simple plumbing procedure to do all of that. You may contact him about it or perhaps he will chime in. He said it dropped his temps by over 30 degrees by running the stand alone cooler with a fan. I believe it was off of some smaller MRAP as they were available on Ebay.

I have an aluminum radiator/oil cooler/intercooler setup as does Profo on his 927A2. It is from an RG31 MRAP. The allison temp never gets above 160. But once again it will not be kind on a transmission during cold weather.

Be careful with the TO-4, thats what I run in my track loader. I believe it’s Cat specific, and if I remember correctly they run a strange chemistry compared to other manufactures. I would think NAPA should be able to get you plain 10w motor oil, detergent or non?

I’ve always thought about adding an oil to air cooler after the stock oil to oil.

simp5782 Did you need to do any major modifications to fit the radiator/oil cooler/intercooler setup? I don not mean making brackets and repluming. I mean like body lifts and all to fit under the stock hood. A coolant filter, block heater and intercooler setup were next after the transmission.

Jbulach The oils I listed including the Napa TO-4 10w all say are acceptable with Allison C-4. Likewise the mobiltrans says its good for C-4, TO-4 and TO-2. The shell tractor fluid list TO-2 and C-4. So you think the Allison should not get a hydraulic oil of any kind? Just plane motor oil? I thought a major and important difference in hydraulic and transmission oil was anti foaming agents.

Thanks.

captain said:

simp5782 Did you need to do any major modifications to fit the radiator/oil cooler/intercooler setup? I don not mean making brackets and repluming. I mean like body lifts and all to fit under the stock hood. A coolant filter, block heater and intercooler setup were next after the transmission.

Jbulach The oils I listed including the Napa TO-4 10w all say are acceptable with Allison C-4. Likewise the mobiltrans says its good for C-4, TO-4 and TO-2. The shell tractor fluid list TO-2 and C-4. So you think the Allison should not get a hydraulic oil of any kind? Just plane motor oil? I thought a major and important difference in hydraulic and transmission oil was anti foaming agents.

Thanks.

Click to expand...

Took me about 4hrs to do it all. It isn't hard to modify it into the truck. Everything clears just fine. You have to do a little hose adapter configuration on some but I made everything from what I had sitting around.

https://www.steelsoldiers.com/showthread.php?169870-M923A1-Aluminum-radiator-install&highlight=

captain said:

....Jbulach The oils I listed including the Napa TO-4 10w all say are acceptable with Allison C-4. Likewise the mobiltrans says its good for C-4, TO-4 and TO-2. The shell tractor fluid list TO-2 and C-4. So you think the Allison should not get a hydraulic oil of any kind? Just plane motor oil? I thought a major and important difference in hydraulic and transmission oil was anti foaming agents.

Thanks.

Click to expand...

I really have no idea, this is one thing I still need to do yet also. I was always under the impression the military used motor oil. I just wanted to make sure you knew what you where buying, sounds like you do. Hopefully someone else can clarify.

The TO-4 at napa today does say it meets c-3 and c-4 specs. I also found that rotella t1 10w meets c-3/c-4. The rotella 15w-40 only meets tes-439. tes-439 looks to be the newer off road spec. Are the newer specs backwards compatible with c-4?