I have an 05 Duromax automatic Allison transmission. After reading many many many posts, am I to assume I put 5w-30 in the transfer case?

I have an 05 Duromax automatic Allison transmission. After reading many many many posts, am I to assume I put 5w-30 in the transfer case?

I run castrol syntec 5w-30 in mine, 2.5 qts. engages and disengages very smooth. Any sythetic 5w-30 will do.:D

Transfer cases acutally come with Dex III or Dex IV. There have been some people switching to 5w-30 motor oil. Use the search button and you will find many posts on this topic.

I always used synthetic ATF in my T-case the first 70K, and it always clunked when engaging, and driving down the road you could always here a hum.
Since I switched to 3 qts of synthetic 5W30 motor oil 25K miles ago, my T-case has never engaged or ran quieter.
I installed 3 qts of oil with the Amsoil pump through the speed senser hole in about 10 minutes and didn't spill a drop. The pump was well worth the $10.

I just changed mine and I run synthetic ATF (Valvoline Dex VI), but I just wanted to also add that I didn't used the pump, and what a pain in the butt it is to get the fluid in thru the speed sensor. Don't even think about the drain and fill without the pump.
x2 with the pump!
:agreed:

Thanks for the replies.

There was a TSB out on these transfercases from the manufacturer (not GM) saying that the trans fluid gets so hot in the case that it disapates so you lose fluid. So they basically said to use 3 quarts of 5w-30 to take care of the problem. The reason for the third quart is to keep it from foaming up. To get the third quart in you just unscrew the speed sensor at the top of the transfer and get it in the best you can. The speed sensor is plastic so BE CAREFUL!

just did this mod earlier today...all i got out of the tcase was barely a quart :( thats why it sounded weird :lol: 3 qts of valvoline 5-30 synthetic did the trick..

just did this mod earlier today...all i got out of the tcase was barely a quart :( thats why it sounded weird :lol: 3 qts of valvoline 5-30 synthetic did the trick..


No leaks I hope. :)

last time down the track it was making a howling sound on accleration and slowin down..:eek:

No leaks I hope. :)

last time down the track it was making a howling sound on accleration and slowin down..:eek:

I think what fbh31118 is asking, is to make sure you don't have the pump rub leak.
Where did the other 3/4 quart of lube go?

I think what fbh31118 is asking, is to make sure you don't have the pump rub leak.
Where did the other 3/4 quart of lube go?
no pump rub as of yet..dont know where it went:(

no pump rub as of yet..dont know where it went:(

It probably vaporized from the heat that the T/C produces. jat.

moved here, I put in 3 quarts of 10w30 Schaeffer's synthetic in mine.
I cut a small funnel off and just dumped the quarts in the speed sensor hole.

BTW, have your driveshaft in or it'll run out the back, even though it's empty.

After you have the extra qt in how do you check the fld level, or just forget about it and check for the pump rub hole??

It probably vaporized from the heat that the T/C produces. jat.
thats what i was thinking..im still amazed though that over a quart vaporized in 13k miles