What's the factory recommended change interval for the rear AAM? What's the recommended weight of gear oil?

steved's Sig:

sdeeter19555@yahoo.com

2004.5 2500 600CTD NV5600 4.10s; FASS; mod'd airbox; Gulf Coast 0-1 bypass; 4" straight through exhaust; second tank setup for a prefilter.

holds 3.83 quarts
Gear oil 75W-90 synthetic or equivalent.

only thing i can find for regular change interval is check the level every 5k and add if needed.

2500HeavyDuty's Sig:

So the GM crowd doesn't have a ridiculous 15k change interval like the Dodge crowd?

We (Dodge guys) were discussing this the other day, and were curious as to the change interval for the GM folks since both use the AAM 11.50 rear axle. Dodge specifies 75w90 and 15k change intervals (front and rear if 4wd).

Seems funny that the same axle, under two different models, would specify completely different maintenance.

i could be wrong, i thought i seen it posted somewhere on the net the regular change interval.

i found the info skimming though my fsm

I garantee you I have 5 trucks with over 200k and at least 15 other trucks between 100-200k that have NEVER had the rear diff fluid changed AND do not have problems.

Rttoys's Sig:

'05 Chevrolet CC/SB Duramax/Allison

Thanks for that info 2500.

Don't get me wrong, I have approaching 200k on my truck, and the fluid has only been drain two times (50k mobile 1, 75k royal purple). I disregarded the recommended 15k change interval because I thought it was excessive. My logic was the simple fact there is no significant differences between this differential and one built 25 years ago...they use similar gears, bearings, races, and seals. I'm not arguing the fact they won't go that many miles, only trying to determine WHY Dodge would specify a 15k change interval.

I would like to see if the GM Owner's manual has a change interval? Dodge has a standalone booklet for maintanence intervals.

Nope. '99 and up only says "check fluid level".

Cool, that's what I was looking for!

75W140 is recommended for towing IIRC

On DP there its recommended 100K change interval posted by a tech several years ago I'm not sure if that was GM or just a general recommendation made by him. Rttoy has plenty of Dmaxs in his fleet so I would trust him. 200K on that nasty break in oil....wow

dozerboy's Sig:

These views expressed on this post are not my own, but rather randomly generated computer gibberish and in no way should be used to judge the author's IQ or mental health.

break in oil is supposed to be swapped out at 500 miles

Show it to me in the GM service manual or owner's manual ('99 and up Silverado)

the only reason to change diff oil is if something else goes wrong and you have to perform maintenance on the actual diff or carrier...other wise leave it alone and worry about something else...that oil will be fine in there

stkdram55's Sig:

Just an Inline 6 Cylinder

Only 2 defining forces have ever offered to die for you.....Jesus Christ and the American Soldier..
One died for your soul, the other for your freedom.

haven't looked in the owners manual, but it is in the fsm

I went 35k before I changed mine.... and I was amazed at how much metal was stuck to the plug(s)....moreso the front than the rear. Definitely recommend changing both probably around the 3k mark for the first time and then probably 50k after that if you use quality oil.

motoguy82's Sig:

2005 Duramax LLY - EFI V2, SCIII w/ 1056, 6" lift, MBRP turbo back 4", +more

First oil change at 65k. Not by choice, but needed to change seals in the rear hubs. It was relatively clean. Changed at 110k, this time more metal, but lot harder towing after the hub repair. Pulling 10k at 85 - 90 down the interstate for 1 hr in and out of traffic does not help. Also added the power adder at 70k. Oil still looked and felt ok, not an excessive amount of metal on the magnet, but some there. Using amsoil in the rear diff now. Need to do the front, but don't have the time or oil. Also changed the trans case to amsoil from the stuff that GM recommends, after the t-case hole issue.