[Vigilante375]

Originally Posted by Stephen12ZL1

use what GM recommends for the rear diff...the synthetic isn't better if it doesn't have the appropriate additive. It is simple to change and you can change it more often with the 88862624. I had a '15 Z/28 which had the rear that required the synthetic you list above. Gear oil isn't like engine oil so the "synthetic has to be better" thing is not a worry at all. Clean gear oil in the diff is the most important so swap it at 500mi & 1500mi when the car is new. After break in follow GM's protocol for track use diff fluid changes or swap it yearly if there is no track use.

Actually..... its every 45k miles per the maintenance schedule of you don't track the car.

[CalgaryZL1]

Originally Posted by Vigilante375

Actually..... its every 45k miles per the maintenance schedule of you don't track the car.

This is my point, if you’re gonna wait 45,000 miles yes you should probably get synthetic and a line on a replacement rear end in my opinion. or you change it every few seasons and put in the recommended oil is since 2016

[Vigilante375]

Originally Posted by CalgaryZL1

This is my point, if you’re gonna wait 45,000 miles yes you should probably get synthetic and a line on a replacement rear end in my opinion. or you change it every few seasons and put in the recommended oil is since 2016

If you're waiting 45k miles if you don't race the car, per the maintenance schedule, to change it out with the recommend fluid, 10-4034, then why get something else?

[Stephen12ZL1]

Originally Posted by Vigilante375

Actually..... its every 45k miles per the maintenance schedule of you don't track the car.

understood but the OP is worried about doing something "better" for his rear diff and changing yearly with the recommended gear oil would suffice keeping the fluid pristine