2021 zr2 electric locker differential oil

Apr 17, 2023
I changed the oil in my rear differential already, unfortunately I did some research after the oil change and taking advice from the guy at the autoparts store. I put in Amsoil 75w90 long life synthetic gear lube, he basically said it is gl-5 approved and doesn’t contain the limited slip additives and is good for my truck. I took a couple bottles and changed out the oil, the test drive didn’t have any issues such as gear whine or anything different sounding yet.

My research shows the amsoil web page stating the severe gear 75w90 with limited slip additive package is the suggested product! Is this just the best product for the diffs and the other stuff the guy gave me perfectly fine? I am finding different information in different places about the right oil to use, of course I looked at the general motors information and it wants me to use a gm product. It requires removing the spare tire, and the diff cover so its not a quick fix, I would be happy to know that the oil I put in is better than a factory fill…but there is soooo much different information out there, I assumed putting in synthetic amsoil gear oil was going to be way better….the more I research now the more I am questioning my gear oil change!

I guess I should also mention that I do not drive through deep water, tow or do any hardcore 4x4ing….and the old diff oil was pretty sparkly, with some very fine stuff on the fill plug magnet. I assume thats normal for the original oil at 35,000 km.
Last edited:
I believe most gear oils have the additive in it by default, now. At least the last gear oil I bought for my limited slip equipped truck did.

However, electronic lockers don't use clutch packs. you should be okay without having the clutch additive.

New gears make a lot of trash during breakin. The sparkles and crud are normal.
I believe the ZR2 has an Eaton ELocker - which does not require any special additives.

What type of gear oil should I use with the ELocker?​

  • Most gear oils are sufficient: a quality, petroleum-mineral based oil is recommended.
  • Synthetic oils and friction modifiers can also be used, but are not necessary.
  • In cold weather conditions, a lower viscosity gear oil (equivalent to API GL-5 75W-90) is recommended.
That makes my day knowing I don’t have to deal with all that time and cost again! Never dealt with changing a differential oil before…be easier if there was a drain plug lol. Thanks for the help!