647

I recently purchased a (new to me) 2010 Express 3500 LT 6.0L V8.

It is in really good shape. Only 52k miles and only minor cosmetic problems (that I see so far).

I'm going through and changing all of the fluids and doing maintenance checks on everything, and was curious about the recommended fluid for the rear differential.

I have a Haynes manual that recommends gear oil of some sort, I don't remember the weight suggested. However, the owners manual suggests using DEXRON VI ATF.

I am inclined to go with the owners manual, but that just seems a bit odd.

Any suggestions?

mountainmanjoe

http://www.vadengmpp.com/owners-manu...et-Express.pdf




You must have been looking at the transfer case.

647

Thank you for the PDF. Nice to have a clean digital copy of it.

Right, I am talking about the fluid for the differential (technically this vehicle doesn't have a transfer case), and the manual indicates ATF for it.

I called a local dealer and talked to the service manager and he confirmed that yes, the differential uses the same DEXRON VI ATF that goes in the transmission.

Go figure . .

mountainmanjoe

what??

Look at the image I posted. It's taken straight from the fluids section of the GM owner's manual for your van. Axle (same as differential) = 75W90. It even gives a part number, and it's GL-5 not ATF.

I have NEVER heard of putting ATF in a diff!

Irish_alley

ive also never heard of that either. the rear wouldnt be properly lubricated and wouldnt last too long

mountainmanjoe

I'm totally perplexed.

Please can you post a picture of the page in your manual where it says to put ATF in the diff?

StanVan

When I Googled this, Dexron IV came up on several sites, purporting to know transmissions/drive trains. Sounds wrong to me, but.....

mountainmanjoe

but... what? Why should I ignore the manual?

647

OK, my bad on this one.

This is what happens when you confuse "Transfer case" for "differential" and don't notice the page in the maintenance section that clearly describes the differentials as "Front and Rear Axle". As this is a RWD, it obviously will not have a transfer case.

It sounded totally weird to me as well to use ATF in a differential, thus my post here to clarify.

Thank you all (especially @mountainmanjoe) for setting me straight.

Now, that I'm straight on using gear oil . . . is there any reason NOT to use synthetic in these machines? I don't mind spending a bit more for quality lubricants to help extend the life of the components.

647

*sigh*

Yes, more RTFM on my part . . . the manual specifially says . . . "synthetic"