Allison oil change which one to use ?

cooldevil · February 21, 2005

hi all im new to this forum and i went yesterday to my dealer and i ask them for changing the oil of my trany and they only have Dexron III oil which is the normal ATF and i ask them if they have the TranSynd they said they dont have them so is thear any other oil that i can use it other than ( TranSynd and Amosil ) and what do you think of Mobil 1 ATF oil is it good for Allison 1000 trany and what about the mobil 1 engine oil fully synth. and one more thing the outer oil trany filter when should i change it after how many miles .

P.S. : the manual said i should use the normal Dexron III oil in the Allison trany

Shooter_va · February 21, 2005

I am running Mobil 1 in engine, changed transfer case to Mobil 1 ATF and when I hit 75K miles, I'll change tranny to Mibil 1 ATF as well.

cooldevil · February 22, 2005

so the transfer case use the same gear oil which is DexronIII

496 CUBIC INCHES · February 22, 2005

I've had M1 ATF in my Allsion for about 25K miles,it works fine. Is your truck new? If its new I'd change the spin-on filter at 5K miles. Otherwise,change the oil and filter at 25K if you tow alot,and 50K if you don't tow.

The T-case uses ATF as well. It's ok to use the M1 ATF in the T-case as well.

496 CUBIC INCHES · February 22, 2005

so the transfer case use the same gear oil which is DexronIII

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Dexron III is not gear oil.

cooldevil · February 22, 2005

my truck is not new i buy it used but i dont know whan was the last trany oil change and whats in the T-case ?

what all of you recommend me to use in the rear axle and the front ?

my truck is 2001 crew cab 4x4 2500HD with allison trany

BADGERMAN · February 22, 2005

I use royal purple in everything, it cost about they same as mobile 1.

496 CUBIC INCHES · February 22, 2005

my truck is not new i buy it used but i dont know whan was the last trany oil change and whats in the T-case ?

what all of you recommend me to use in the rear axle and the front ?

my truck is 2001 crew cab 4x4 2500HD with allison trany

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The front and rear axles use a 75W-90 gear oil. For the rear GM reccomends their own synthetic gear oil which is purple and smells like grape juice. The downside is that it costs about $25 per qt.,and you'll need 4 qts. My truck is a 2001 and only reccomends the "grape juice" from GM. The newer trucks 04',05' reccomend the "grape juice" or a GL-5 rated 75W-90 gear oil. I think GM realized people weren't going to spend $25 a qt. for gear oil.

I'm changing out the front and rear diffs this week,and will be using Mobil1 75W-90 synthetic gear oil. You need four in the rear and two in the front. The M1 is about $7.99 per qt.

If you don't know the history of the truck,I'd change out all the fluids now. If you drain the tranny and replace the filter you'll need 7.5 qts of Dexron III rated ATF. Don't buy the Allison spin-on filter from GM,they charge $20-25 for the same filter an Allison dealer charges $7 for. When you change the filter,you'll see a donut shaped magnet on top of the old filter,be sure to wipe the magnet off and put it on top of the new filter.

Like I said,the T-case uses the same Dexron III rated fluid. It uses 2 qts.

Anything else?

cooldevil · February 23, 2005

so im not sure to change the front dif. oil and the rear because im afraid to damege it with changing the oil

496 CUBIC INCHES · February 23, 2005

so im not sure to change the front dif. oil and the rear because im afraid to damege it with changing the oil

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How would you damage it? Its easier than changing the motor oil. The diffs have a drain plug and a fill plug. You don't need to remove the diff cover,or replace any gaskets.

Freyguy · February 23, 2005

Check this thread out.....has some pics that might help:

http://www.gm-trucks.com/forums/index.php?...topic=34659&hl=

As you can see, i did mine with no problem. I put Mobil 1 in my front/rear diff because I had a gift card for Pep-Boys. I'm running all AMSOIL in other places and I'll switch to that when it's time to change. I have AMSOIL 0W30 in my engine, and the ATF in the Tranny and T-Case. So far, it works great. I didn't really notice any mpg improvements that some talk about, but no big deal. I'm just happy knowing my engine will last forever now.