Duramax Rear Differential 12,000 on fluid/25,000 total miles

[Job]

I got some synthetic Delo at AZ 75w 90 and it does say meets 500000 mile specs for certain axle companies. Also got Delo ESI 80w 90 thru Walmart for under $7/qt, doesn't say synthetic. Both Delos have GL5 GL4 and MT1 ratings.

 

[stockrex]

My experience:

1. factory fill - swapped at 11k miles and it felt like a new truck, I gained some power.
I used synthetic 75w90 without any addy, I think I used mobil 1.

I will do it again in another 20k miles as I did not really get a chance to break in my rear end, the duramax guys say, tow a 15k trailer for few thousand miles and around the city and you are good.

 

[CT8]

Originally Posted by PiperOne
No oil analysis on the rear ends. If they are quiet and don't clunk we leave them be. Gear oils have gotten sooo much better over the years as well as the metallurgy in the rear ends we just don't have issues. Class 8 highway trucks (semi) are all over 500,000 mile drains and warranty approved at that interval.
They have filters.