97 Chevy 4x4 gear oil question?

(2011-12-22 15:15:11) 1. Furball Says: I have a 97 Silverado 4x4 that needs gear oil in the rear differential case, my Chilton book says it takes 80W90 gear oil in the rear, and 80W90GL5 in the front, but all I can find where I live is the 80W90 GL5 or 80W90 HypoC Castrol oil, so I would like to know if either of these would work in the rear case, and if they would blend with the oil that is already there?
Any answers would be appreciated.2. Kevi Says: GL5 is a spec for oil , it is fine for your application.3. H.M.C speed Says: You do not "blend" gear oil. (or are you just adding some?)
To change it, you need to take the cover off & all the old stuff drains out. (best thing to do!) Tag: 97 Chevy 4x4 gear oil question?