75-90w synthetic blend

[chasenfish16]

My 2000 chevrolet Silverado Z71 calls for 75-90w synthetic fluid for the rear diff. and 80-90w for the front diff. I went by the Chevy dealer and they wanted $26 dollars a quart for 75-90w synthetic. I went by the auto parts store and they have 75-90w synthetic blend not straight synthetic for $5 a quart that still has the GL5 designation. Would this be okay to put in both my front and rear diffs?

[fossil]

Nope, Only synthetic 75W-90 in the rear diff. This due to the very tight backlash and different pinion to ring gear design from the older series.

You can use whatever you want in the front diff. Also, no additive required if you got the G80 (made by Eaton) as it is a mechanical locking diff...no clutch packs in it.

[redvett]

If you live in a colder climate where winters got below zero its reccomended with auto-trac to use synthetic 75W-90 in the fron axle to avoid wear on the clutch packs in the transfer case. There is a service bulletin on this.

[asepgrad98]

lots of guys on here run Mobil1 gear oil with no problems.

[az'03Silverado]

you can get Mobil 1 or even Royal Purple for like $9-$12 a quart at Checker, Napa, or Auto Zone. I've been running Mobil 1 in my G80 with no problems at all.

[chasenfish16]

So as I can tell from this forum most people use either the royal purple or the Mobil 1 75w90 synthetic in there front and rear differentials.