Valvoline Synpower 75w90, 30k miles, 04 Duramax RD

[TXHunter]

Same thing here, replaced the fluid at 30k in favor of Amsoil Severe Gear 75w90. Will do another check after 40k miles on the new gear oil.

 

[chubbs1]

Excellent!

 

[dnewton3]

Looks good. Very good, actually. You had 50% less Fe wear metals, all other metals are very low, and yet you ran 20% longer than the "universal average". Excellent! Thanks for this UOA. This fluid is what I currently have in my AAM rear diff in my 2006 Dmax. Nice to see a similar vehicle with such a good report. I see that your other UOA (front diff) did very well also. Overall, this makes me feel comfortable with my choice of the SynPower. It was on sale at Napa for good price; 8/qrt as I recall, last summmer.