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2002 Chevy Duramax Front and Rear Diff. fluid

50K views 11 replies 7 participants last post by  Dirtbikindad393 
#1 ·
I need to change my front and rear differential fluid but I am unsure on how much fluid to use and what the correct way to go about it. I am certain I could figure it out but I don’t want to risk screwing anything up. I talked to a high performance diesel mechanic and he recommended Schafers synthetic 80/140 Is this a good choice? Any help is appreciated.
Thanks
 
#4 ·
So the recommended weight is 75-90 and you will need 6 to 7 quarts to do both differentials. You will wont to get yourself the little pump that goes into a 1 quart bottle to pump it into the fill hole on the diffs.
 
#5 ·
Redline Shockproof...
 
#6 · (Edited)
Diesel Pete...The answer to your question is the front diff will take just short of 2 qts 75W-90 and nothing else. The rear will take just short of 4 qts so you will have to buy 6 qts total of your fluid to service a 4wd and that takes into account that you have a stock rear diff cover.

Now the manual says use 75W-90 you may use 75W-140 as recommended by your guy but remember that the thicker the fluid the longer it takes to warm up in cold weather. It will also reduce fuel mileage slightly if you care about that. If you want to go inbetween that Amsoil makes a 75W-110 Severe Gear for a lighter weight oil than 140 but more protection than 90. I suggest you buy the hand pump to make the job easier and cleaner.

If you decide to use Amsoil Severe Gear warrantied for 100k miles please call me toll free 855-MAD-JACK and we will get you set up with what you need. We stock all 3 weights of Severe Gear 75w-90, 110,140 ready to ship. :thumb
 
#7 ·
Amsoil is a great oil I have it in front and rear differential .
 
#10 ·
Pardon the hijack but with regards to synthetic in LSDs, is there anything to be concerned about? I've been a big Amzoil fan for a while now. I did have a complete bearing failure on the rear gear carrier in my gas 2001 CCSB 4WD with 100k on it while using Amzoil, but I'm not sure I'm ready to blame Amzoil given some of GMs bearing quality.

What about friction modifiers? Do you need them with synthetic, with the plates slip more with synthetic?
 
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