front diff oil changed under warranty

[noviceowner]

Called 4 dealerships here in Maine when I read the GMTechLink reference to mineral based possibly not lubricating FRONT pinions adequately in -12F temps. 3 didn't know about and didn't want to know about it. One, Forest City in Portland, took the time to research the issue and is doing the change out to syn under warranty. Mike Abbott, the Service Manager there is awesome. Do any of you run 75w140 in your REAR diff for towing? That's what is specified in my manual for towing instead of the 75w90 for non towing. The service dept can only find that spec for 1 tons, not for the 2500HD. We agree that it is close enough, but I wanted to check with you all before I had that changed at the same time as the front as I'm at 1,300 miles and overdue. While I haven't towed yet, will be hauling horses this summer. Thanks for any info! Wendy
03 2500HD CC SB D/A

[ 02-19-2003: Message edited by: noviceowner ]

[ 02-19-2003: Message edited by: noviceowner ]</p>

[a64pilot]

Glad that you have found that (Gem) of a service dept. IMHO they are rare and far between.
I run the heaver weight oil in my diff. and am happy with it. Where I live it does not get cold, which may be something for you to consider if you switch to a heavier lube.

[JimWilson]

Wow, a real dealer. And I thought they were only in fairy tales. :D

The 74w140 is for heavy towing, so unless you tow a lot, and you live in a relatively mild climate, I wouldn't do it.

[ 02-19-2003: Message edited by: JimWilson ]</p>

[wakely]

noviceowner,
which GMTechLink did you reference the front diff?

JimWilson,
Where did you get your 4-way headlight conversion?

Thanks, wakely

[noviceowner]

Hi Wakely. I used the link posted in another message on the dieselpage forum. Try this
http://service.gm.com:8083/gmtechlink
That should get you there-if not, do a search for the address-it's been posted a few times. In the table of contents it lists the reference to the front differential. I'm getting a lot of different opinions on the 75w140 for the rear. I feel like I've "asked the audience," "phoned home," and now I'm at "50/50!" :eek: It's scarey out here! The manual does say to use the heavier weight for towing, and I wiil be pulling a heavy trailer this summer. Thanks to those that replied. Any other opinions out there? :(
Wendy
03 2500HD CC SB D/A

[ 02-20-2003: Message edited by: noviceowner ]</p>

[JimWilson]

wakely;

From here... http://www.stylinconcepts.com/parts.cfm?categoryid=26&subcategoryid=185&partfamilyid=132

[MadDuraMax]

This bulliten addresses the possible requirement for a synthetic oil at low temperatures. This is due the the pour point of synthetics being at -52+/- or so verses the dino at around -20f.

A 75W-90 syn verses a 75W-140 syn will have very similar cold viscosity characteristics. The 75W-140 is only "thicker" at high temperatures!

Lets compare apples to apples!

Mark

[ 02-24-2003: Message edited by: MadDuraMax ]</p>