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Toddster
10-07-2002, 16:34
Bought 4 quarts of GM "Grape juice" today @ $26 bucks a quart and the diff still isn't full ! What does the G80 hold ? Is this **** a rip off or what ! It's not even a full synthetic ! If I only knew before I put it in......
mackin
10-07-2002, 17:14
Toddster

I put nearly 5 QTS in mine.......===>Mobil<==== :D .....What can I say take your own advice in the Alley,Alley post........ :D :D ...... I used Amsoil synthetic...........

MAC
mdrag
10-07-2002, 18:02
Toddster,

Before the Mag-Hytec was installed on my '01 with the G80 - a drain and refill of the rear diff took slightly less than 4 qts. The '01 Helm's manual indicated 3.83 qts. I did not bother trying to lift each side to drain the lube from the axles.
Jim Rokon
10-09-2002, 04:56
I read in an earlier post that Eaton (Ralph Holmquist ) recommends 75w-140 synthetic gear lube if all we do is pull very heavy trailers, and to change it the first time at 500 miles.

Naturally I didn't read this until I had over 3400 miles but now is better than at 20,000. Does anyone advise against this heavier oil?
Idle_Chatter
10-09-2002, 05:12
Jim, I had the dealer change out both my diffs after 500 miles of break-in (ran in 4-wheel for about 150 or so on dirt roads to give the front some wear-in)as I was making a 3000 mile trip to and from Texas a week after purchasing in Wisconsin. I changed my rear out at 23,150 miles and put in Amsoil 2000 synthetic 75W140, not because I was doing heavy towing, but because I had 8 qts of it on hand that I had purchased and not installed in my 99 6.5TD Tahoe. I've had no problems running that lube and now at 34,400 miles. I am considering stepping down to 75W90 as the weather cools off. I just made the second change to the front end at 33,000 miles and put Amsoil 75W90 in there.
GMCTRUCK
10-09-2002, 11:31
Changed mine yesterday. 1300 miles, black and ugly. Drain plug had 1/8 inch of metal build up on the end and this truck hasn't towed yet. Took 4.5 quarts of Mobil 1 to refill and that was without tilting the axle to drain the tubes.
turbolag
10-09-2002, 11:57
Has anybody removed the cover and if so do you need a gasket? Thanks
hoot
10-09-2002, 12:31
You definately need a new gasket. The old one ends up being a pile of paper after tearing and scraping.

Or you can use the good goop GM uses on it's other components.
mdrag
10-09-2002, 13:39
Turbolag,

Check out this topic:

http://forum.62-65-dieselpage.com/ubb/ultimatebb.php?ubb=get_topic&f=7&t=004040

mdrag

[ 10-09-2002: Message edited by: mdrag ]</p>
Maverick
10-09-2002, 22:29
Just changed mine today.

Almost 5 in the rear diff.
2 qts in the front diff.
Almost 3 in the T-case.
10 qts in the engine.
Tudge
10-10-2002, 07:04
Just changed mine last weekend - I did not jack up the rear end to drain the axle tubes. I ended up putting in 4 qts of grape juice and could feel it with my pinky finger just below the fill hole.

That raises the question - is the rear end supposed to be filled to the bottom of the fill hole??? Is that the same procedure for the front differential as well????

Thanks
Mudflap
10-10-2002, 14:51
I tried filling mine above the bottom of the fill hole but it kept running out!

(sorry)
DmaxMaverick
10-10-2002, 15:49
GM recommends filling the rear end to 3/8 - 1/2" below the bottom of the fill hole. Why they didn't position the fill hole where the level should be is beyond me. I've always filled to the level of the hole. I do it know with the HD and it takes right at 4 qts. I'd do it like GM recommends, but I can't fit my ruler in that little hole.
mdrag
10-10-2002, 19:08
From the 2001 Helm's manual for the 11.5" differential:

The lubricant level should be between 0-10 mm (0-0.4 in) below the fill plug opening.

mdrag