rearend fluid

[PONCH]

anyone running synthetic in the rear end? What are the results?

Thank You

[ADub]

I was under the impression that the trucks came from the factory with synthetic.

[DmaxMaverick]

Originally posted by Ponch:
anyone running synthetic in the rear end? What are the results?

Thank You The factory fill is synthetic. AAM, the manufacturer of the rear end, specifies ONLY synthetic lube. Using a dino lube would likely cause failure, and deny warranty coverage.

GM recommends their lube, affectionately refered to "grape juice", as the only replacement lube. Only place to get it is GM.

On the other hand, I (and many others) use a synthetic of another brand. My choice is Amsoil Series 2000 75-90. It has worked very well for over 80K. I have changed it twice since the original fill, and the lube appeared "good as new" each time. The first change, getting the factory fill out, was absolutely ugly. Definately follow the recommendations of the long term members here, including me (as well as AAM), and change that factory fill after no more than 500 miles of towing, regardless of what GM recommends, which seems to change like the weather. Once you pull the drain plug, you'll see why.

[angus]

I will be changing my rear end fluid this weekend. Does the plug on the rear end housing require any thread sealer, or is it a taper fit like the plug on the oil pan?
Thanks for any info.

[Idle_Chatter]

I'm not sure what you mean by "taper fit" on the oil pan, Angus. Mine has a shoulder with a sealing washer. The rear diff fill plug (on the rear of the cover) also has a shoulder and sealing washer (white nylon). The drain plug on the bottom of the diff has a shoulder and black rubber seal, also contains a magnet. Just make sure the washers are clean and reinstall, no sealant needed.

[k1rod]

Definately follow the recommendations of the long term members here, including me (as well as AAM), and change that factory fill after no more than 500 miles of towing, regardless of what GM recommends, which seems to change like the weather. Once you pull the drain plug, you'll see why. Yea and amen! I changed the oil in my differential last week and it was some of the vilest stuff I have ever seen. It was jet black with a high density of metal in it. It looked like metalflake black. Some of it looked to be about as thin as water and it blew nasty black bubbles as it drained. There were little chunks of metal and a metallic paste all over the drain plug magnet. The smell was something that will take paint off walls. I tossed my clothes into the laundry room afterwards and my wife about gagged when she went in there the next day. I only have 5400 miles on this truck and I have only towed a 6000 lb trailer for about 300 miles. If you haven't changed yours yet, I would do it very soon. Mine was so rotten, I am going to change it again in another 5000 miles. Best -rod

[PONCH]

dma

[PONCH]

DMAX IS THE AMASOIL YOUR TALKING ABOUT 75W-90 SYN EP LUBE?

[DmaxMaverick]

Originally posted by Ponch:
DMAX IS THE AMASOIL YOUR TALKING ABOUT 75W-90 SYN EP LUBE? It is "Series 2000 SAE 75W-90 Synthetic Gear Lube". I'm not familiar with "syn ep lube". The Series 2000 is what Greg Landuyt recommended early on (back when the question first came up in early 2001), and he indicated it is an upgrade from the standard syn. lube. It's not lacking anything that I can tell. The diff. temp seems to be under control, and it doesn't appear to have induced any wear. Rear end is still very tight and quiet. No seal leaks.

They also have the same stuff in 75-140, for frequent heavy towing in extreme heat. This is the viscosity GM recommends for those conditions. I haven't found a need for a lube that heavy, and I tow 12K# in CA summers (100

[PONCH]

AMSOIL ORDERED----They suggested severe gear 75-90 instead, so that's what we'll try!

Thank you all!
SEE YA BYE

[JD Diesel]

Have omly pulled my trailer 50 miles. Plan on changing rear oil about 4000 miles. yall think that would be OK. plan on using amsoil severe duty 75 90. :cool: P.S. I really love this place.

[ 05-20-2005, 06:08 PM: Message edited by: JD Diesel ]

[jbplock]

Moved to the 2500/3500HD Trucks & Drivetrain (http://forum.thedieselpage.com/ubb/ultimatebb.php?ubb=forum;f=11) forum.

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