How many miles - major engine or trans issues?

jrhaines2 · March 21, 2019

On 12/11/2018 at 11:30 AM, seamus2154 said:

In my reading on these forums I have seen several with trans failures from 160K-200K. Most state no maintenance. I find many people to neglect/forget to ever service their trans and differential. I will be servicing using the severe service recommendations and hoping for better. I swapped the stock crap rear differential fluid over to Amsoil early at 5K and will do my trans at 50K intervals. I do tow occasionally but I am in Florida heat all the time.

What differential fluid is used from the factory? I think it's almost unheard of a differential going bad is why I ask.

KARNUT · March 21, 2019

My brother in law has had several Tahoe- suburbans and a pickup. They buy cpo or used. They are used as the main ride for 200K then he puts another 100K on. One required a rear end replacement. He just bought a 13 Tahoe first cylinder deactivation vehicle for him. The one he took weathered well still looks good.

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seamus2154 · March 22, 2019

8 hours ago, jrhaines2 said:

What differential fluid is used from the factory? I think it's almost unheard of a differential going bad is why I ask.

An AC Delco 75/85W. I have owned 4 of these trucks and changed the fluid on 3 of them early on. All were dirty break in looking fluid, not pretty. I was very happy I had changed it as I tow a bit. Amsoil is fantastic stuff. Not many diff failures at all, but I maintain to keep things for a long time.....which didn't happen with any of these trucks!

jrhaines2 · March 22, 2019

12 hours ago, seamus2154 said:

An AC Delco 75/85W. I have owned 4 of these trucks and changed the fluid on 3 of them early on. All were dirty break in looking fluid, not pretty. I was very happy I had changed it as I tow a bit. Amsoil is fantastic stuff. Not many diff failures at all, but I maintain to keep things for a long time.....which didn't happen with any of these trucks!

It's always good to change the fluid from break in.I thought you were talking about the quality of the GM fluid.

seamus2154 · March 22, 2019

8 hours ago, jrhaines2 said:

It's always good to change the fluid from break in.I thought you were talking about the quality of the GM fluid.

The GM fluid is synthetic but is thin and IMHO not looking too good in less than 20K. I do oil analysis on most fluids but didn't on this as nothing would sway me to use it again. I have used Amsoil for 20 years w/ analysis and it looks like new 30K later and didn't need changing. There is not a lot going on in a properly set up differential, broken in correctly. I doubt there could possibly be an issue using the GM fluid. I just wanted better.