Front And Rear Diff Fluids?

dbefay · July 2, 2008

So I was going to change the front and rear differential fluids today but I think I bought the wrong oil. Two different part stores told me two different fluids. I ended up buying a gallon of Valvoline 80w-90 to cover both of them. Now ive been reading that I need 75w-90 synthetic in the rear. Will I notice a difference? Will it affect anything if I dont use 75w-90? Also how much do I need for each? I have a 2000 silverado 1500 z71 with 3.73's and a G80. Thanks in advance!

mi.bowtie · July 2, 2008

80/90 front. 75/90 syhthetic. Must use in rear. Fill both till it comes out at fiil plug,

MS3DALE · July 2, 2008

And DO NOT add any kind of additive,Its not needed or recommended by GM.

dbefay · July 3, 2008

Alright, thanks guys! You said to fill till it comes out of the plug, about how many bottles of each will I need? This is becoming an expensive day! My transfer case is f**ked too. I found out there was a hole in it after I bought it. It was apparently fixed on the inside but they just RTV'd the hole. Well me and my bro have been under the truck for about an hour and we've filled 3 holes so far. Is there a weep hole or anything on the case so I know not to jbweld that? lol. It was making a loud noise so i filled it with about a half liter this morning. Now draining it the fluid was brown. There was a couple small pieces of metal and some bigger pieces of rubber. Any ideas what those would be? Should I be worried about it failing any time soon? I cant afford a $1500 tcase. Thanks again!

MS3DALE · July 3, 2008

Alright, thanks guys! You said to fill till it comes out of the plug, about how many bottles of each will I need? This is becoming an expensive day! My transfer case is f**ked too. I found out there was a hole in it after I bought it. It was apparently fixed on the inside but they just RTV'd the hole. Well me and my bro have been under the truck for about an hour and we've filled 3 holes so far. Is there a weep hole or anything on the case so I know not to jbweld that? lol. It was making a loud noise so i filled it with about a half liter this morning. Now draining it the fluid was brown. There was a couple small pieces of metal and some bigger pieces of rubber. Any ideas what those would be? Should I be worried about it failing any time soon? I cant afford a $1500 tcase. Thanks again!

I have no idea what the metal and rubber are (The rubber could be the RTV sealant) But one things for sure.....It can't be good