Hey everyone, I'm going to be replacing the fluid in my front and rear differentials this weekend, and it says to use 75W-90 Synthetic Axle Lubricant in the manual, use either the GM stuff or a 75W-90 Synthetic Axle Lubricant that "meets GM Specification 9986115."

I was looking at the AMSOIL Severe Gear 75W-90:

http://www.amsoil.com/storefront/svg.aspx

However I'm not sure if it meets GM specs 9986115.

Has anyone else had this issue? Are there any other fluids from other brands I could use? Any input would be great, thanks!

 

I would think the Amsoil would meet or beat the GM oil. When I had mine changed at the dealership they did not add any modifiers to the oil for the posi limited slip. Not sure if the Amsoil is the same. On my Toyota Land cruiser has the same thing done at the dealer. When I got it back it would clunk around corners. Dealer added the modifier and the noise went away. MAy not hurt to add some while your changing the oil.

 

The Amsoil will work fine. It is great stuff. The GM fluid is also great. Made for GM by Mobil so it's probably Mobil 1.

 

I used Mobil-1 75/90 Synthetic gear oil. been like 6,000 miles and no issues. Did it myself and saved HUNDREDS vs. dealership. H2 has its own fill and drain plugs. Took like 5 min a diff.