Changing differential lube for the first time need advice.

[rwh531]

I have a 1995 Gmc jimmy Slt and need to know if limited slip gear oil is required as I am popping open the pumpkin and replacing the gasket (I've got the cheap supratech 80-90w from walmart and want to ensure I wont destroy anything using it (I don't tow anything if that matters)

[newdude]

No friction modifier on the G80 lockers.

[rwh531]

So the Differential shell is pretty well caked with 20+ years of grime am I right to assume there isn't actually a fill plug and that I will have to fill via the breather tube port ?

[elcamino]

There is a fill plug.

 

[rwh531]

guessing I just need to use an extension bar from my socket set to unscrew that ?

[newdude]

Fill plug is on the passenger side of the pinion housing. 3/8" drive.

[rwh531]

you guys are awesome, Now I just got to figure out what size socket I need to buy to crack the drain/fill plugs on my transfer case.

 

In case you guys were wondering the truck is a flood survivor, Just got to make sure it survives another 6-8 months as it's currently my only transportation only noticeable problem is I sometimes hear a grinding noise when in 1st and it feels like I am driving with the E-Break on until it shifts into a higher gear but since it only happens shortly after I disengage 4wd I think the transfer case could just be failing to fully disengage. would suspect the transmission but it hasn't slipped not once

[mookdoc6]

Hard for some to believe but there is a square socket made for this intended application.....I was trained in the "rust belt" use the correct tools and think twice about breaking anything loose in the "rust belt"

[txab]

loosen/remove fill plug before removing diff cover

[Motor City Rick]

Since you mentioned your truck is a flood survivor, if you find the dope is saturated with water, make sure you tip the left and right side axle tubes also to get "all" the scuzzy dope out. This might take a few minutes for each side. If it's real bad, then you'll have to pull both axle shafts to blow / flush the axle tubes out with compressed air / solvent. Make sure the dope your putting in has a SAE 80W-90 GL5 rating. Be careful on anything Wal-Mart sells.