I dont know if they come stock with synthetics or not, but is there anythign wrong with doing a flush on the diffs and trans (thru the dealer) and replacing the fluids with synthetics?

Thanks
Matt

 

They used non-synthetic motor oil in mine, I am not sure about the transmission or dif fuilds though.

I like synthetics personally, they offer superior protection and durability. The only downside is they tend to be a more expensive. If you can afford it I say go for it!

 

I had Sewell Hummer, Dallas do my 50K Service Package:

Diffs, 89021677 - GM Synthetic Axle Lubricant- 75W-90 Weight, $22.00
Tranmisson, Transfer Case 88861003 - GMDEXRONŽ-VI ATF, $7.36

Since my first oil change, Castrol 5W-30.

Gotta say, Sewell has given me a great service experience over the years

 

You're diff's and trans already have synthetic fluid in them. Replace with synthetic.

 

great thread

 

Excellent input thanks for the advice guys. I'll go with synthetics all the way