Rear End Gear oil

[mrriverajr]

How do you change out the gear oil in the rear end? How much oil do you put back in? Where do you put it back in? How do you drain it?
Sorry for the dumb questions but I have never done it before and want to be fully prepared this weekend when I do it.

Thanks Guys your the best.

[00s104.3]

First remove the lower bolts around the differential cover and just loosen the top ones.

Then use a screwdriver to pry open the differential cover allowing the fluid to drain into a bucket or drain pan.

Once all the fluid drains out remove the rest of the differential cover bolts and the cover.

Use a clean rag to wipe the cover off and clean up the puddled up gear oil in the bottom of the differential.

Using a gasket scraper or screwdriver scrape away the old gasket from around the differential cover and the differential case.

Apply a thin coat of RTV sealant around the inside edge of the differential cover and stick the new gasket onto it making sure the holes line up

Bolt the cover back on using a criss-cross pattern (don't know what the bolts should be torqued to, just make sure they are tight)

On the backside of the differential there is a fill hole (mine is on the passenger side) You may need to clean off the dirt to find it but it is there. Unscrew the plug and fill the differential to the bottom of the fill hole. (mine took about two quarts) Put the plug back in and your done. Check the fluid level again after you drive it some.

[95 S_Trucker]

I would take out the fill plug first before you take off the cover. That way, if you cant get the plug out, your not stuck with a rearend that you cant get any fluid into.

Those fill plugs can be a pain to get out. Buy a 3/8 square key that you can put onto a socket or breaker bar. Dont use a socket extension.


I changed the diff fluid on my old 91 about a year ago. I took the cover off first and then tried to get the plug out. I rounded off 2 socket extensions with a breaker bar and still couldnt get it off. I ended up taking the little filter off the breather hose and put 2 quarts of fluid in that way. I just hoped that I put in the correct amount of fluid in.

Anyway, good luck.

[poconojoe]

Quote: Originally Posted by 95 S_Trucker

I would take out the fill plug first before you take off the cover. That way, if you cant get the plug out, your not stuck with a rearend that you cant get any fluid into.

Those fill plugs can be a pain to get out. Buy a 3/8 square key that you can put onto a socket or breaker bar. Dont use a socket extension.


I changed the diff fluid on my old 91 about a year ago. I took the cover off first and then tried to get the plug out. I rounded off 2 socket extensions with a breaker bar and still couldnt get it off. I ended up taking the little filter off the breather hose and put 2 quarts of fluid in that way. I just hoped that I put in the correct amount of fluid in.

Anyway, good luck.

Why didn't you just get a 1/2" drain plug and a 1/2" fine threaded nut and braze the nut to to inside of the cover at the correct height for the fill level? It doesn't mater if you get an air tight braze, since the gasket on the drain plug seals against the cover. I've done it dozens of times.

[S15vortecpwr]

the rear end holds 2 qts. If you have a LSD don't forget to add the additive. I have Royal Purple 80-90 in the 01 GMC, Wal-mart brand 80-90 in my 94, and Mobil1 75-140 in my TA.

[mrriverajr]

Thank you so much guys for the tips I will do it this weekend.

[00s104.3]

Quote: Originally Posted by mrriverajr

Thank you so much guys for the tips I will do it this weekend.

Glad to help.

[SnoMan]

What is the LSD additive i apparently need?

[95 S_Trucker]

if you have a stock g80 there is no need for lsd additive.

[S15vortecpwr]

the addidtive is for if you have installed a eaton posi or any other clutch type carrier. RP oil have the additive already added to the oil.


ALSO thanks for searching.

[MTchevyS10]

Quote: Originally Posted by SnoMan

What is the LSD additive i apparently need?

Most quality synthetics are already engineered to not need an additive for this, as mentioned.

[MTchevy1]

You stole my user name.

[jetski]

10-4. besides that the oil pan looks like a nightmare to remove if had to..lol 2002 s10. 4 smoker. 5 speed.

[pastorbud]

If the plug is stuck in (mine was), there is a vent tube coming out the top. I took off the clamp and pumped in the lube through there with a little hand pump like this one.

http://www.amazon.com/Custom-Accessories-36670-Pennzoil-Transfer/dp/B001DKQZ9Q

http://www.amazon.com/Custom-Accessories-36670-Pennzoil-Transfer/dp/B001DKQZ9Q

If you use a piece of brake line or other stiff, narrow tube, it make less mess and lets the air vent out around it as it fills.

Autozone site list 1-3/4 quarts as the capacity.
http://www.autozone.com/autozone/rep...yNameForTitle=

[ranman]

Quote: Originally Posted by poconojoe

Why didn't you just get a 1/2" drain plug and a 1/2" fine threaded nut and braze the nut to to inside of the cover at the correct height for the fill level? It doesn't mater if you get an air tight braze, since the gasket on the drain plug seals against the cover. I've done it dozens of times.

Is there an easy way to determine the correct height location on the cover? Hate to keep trying till you get it right.

[Chiefron]

Or you can get a billet aluminum diff cover from Summit or another aftermarket supplier that has a drain plug in it for future lube changes. I also recommend the synthetic gear lube. For the few extra bucks it offers a lot of benefits, not to mention at least twice the life.

[57 Handyman]

When I need to scrap old gaskets off of a part, I have found that using single-edge, straight blade razor makes the job a whole lot easier. The sharp blade will cut thru all of the crude and any sealers plus will leave a clean smooth surface.

[S15vortecpwr]

Quote: Originally Posted by ranman

Is there an easy way to determine the correct height location on the cover? Hate to keep trying till you get it right.

if you can get the plug on the diff out, just fill it up til the oil runs out. it will be full. it will hold right at 2 qts of fluid.


i clean my parts off with a gasket scrapper, but i use a gasket and no RTV so it comes off pretty easily.