GMT800 rear end question

[shibbershabber]

I recently bought a 2002 Tahoe... within a week it began squealing from the rear end.

Took it in to get a rebuild at a local shop. Had nothing but good reviews.



Picked it up and he had filled it with regular ol' 80w90 gear oil.

To my knowledge, these needed a 75w90 synthetic...

He said that it is just fine and that all of the new parts 'seated' best in 80w90 for a 500 mile break-in & that after that 500 miles I can drain and fill with a synthetic if I wanted.... but it would be fine leaving the 80w90 in there.


Is this guy full of ****?

Hes been in business forever and I have not seen a single negative review.


I just drove the 500 miles and am looking to fill it with the synthetic.
In this process, should I speed up the oil change interval to flush the 80w90 out of there or will a regular drain and fill be okay?

 

[kennythewelder]

Any brake in needs to be done with convent oil. Synthetic oil will not allow for a proper brake in due to its properties. If you just drain and refill you should be fine. To get all of the old oil out, you would have to remove the diff cover and clean the diff out with brake parts cleaner, but that isn't necessary. The little bit of convent oil that remains after the drain, wont bother anything.

 

[shibbershabber]

Sounds good.

500 miles a good enough break in?

 

[kennythewelder]

Sounds good.

500 miles a good enough break in?

Yes