72 differential oil/fill line?

[dukcaln]

what do you all suggest for differential oil and how much do I put in... is there a fill line or something... I am getting ready to go out and take cover off cause it is leaking from bottom (since I bought truck) and re-seal. Then put new oil in..... what do you all suggest, is there a simple way to know when it is full

[TobyArnot]

Me too!!

[racer57]

Always been told fill it until rear end oil comes out fill plug.
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[AirSpeed]

Originally Posted by racer57

Always been told fill it until rear end oil comes out fill plug.
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That's always been my understanding, fill it up until it runs out.
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[bosco200]

3-4 quarts, Royal Purple is good stuff

[fastwillie 696969]

remove the drain plug first before poppin the cover off ,basic open diff. 2qts 75-90 w gear oil Quaker state or Lucas lubrication ,take a ball peen hammer and slight tap the bolt holes flat and clean off surface to prep for silicone gasket sealer ,install the cover with the rtv ,tighten the bolts 20 ftlbs ,add oil to the drain hole on the side of the rear just when it drips out put the plug in
if its posi used the synthetic oil

[toolboxchev]

Originally Posted by fastwillie 696969

remove the drain plug first before poppin the cover off ,basic open diff. 2qts 75-90 w gear oil Quaker state or Lucas lubrication ,take a ball peen hammer and slight tap the bolt holes flat and clean off surface to prep for silicone gasket sealer ,install the cover with the rtv ,tighten the bolts 20 ftlbs ,add oil to the drain hole on the side of the rear just when it drips out put the plug in
if its posi used the synthetic oil

Be sure to let your Black RTV to cure and dry overnight before filling with gear lube.

Just a safe way to ensure it does not leak. I always use a gasket and and smear a light coat of RTV on both sides of it.

[dukcaln]

cool thanks..... I don't think it is posi, unless it came that way from factory... I think it is the factory 3.73

[eagleuh1]

Put the additive in for Posi too if you have a posi. I like to overfill mine a little so it runs out to the axle tube ends. I just force it in after it overflows a little then put the plug in real quick. Jim

[RenoKeene]

Originally Posted by eagleuh1

Put the additive in for Posi too if you have a posi. I like to overfill mine a little so it runs out to the axle tube ends. I just force it in after it overflows a little then put the plug in real quick. Jim

What brand of synthetic do you use and what additive?
Thanks

[cdowns]

Originally Posted by RenoKeene

What brand of synthetic do you use and what additive?
Thanks

i use royal purple 2quarts for a 12bolt rear// no drain plugs on a 12bolt/ no additives required with royal purple or most synthetic gear oils nowadays

check the bolt holes of the cover and make sure they are flat overtightening causes them to "bell" out and cause poor sealing and leaks

[Siedl]

Originally Posted by cdowns

i use royal purple 2quarts for a 12bolt rear// no drain plugs on a 12bolt/ no additives required with royal purple or most synthetic gear oils nowadays

check the bolt holes of the cover and make sure they are flat overtightening causes them to "bell" out and cause poor sealing and leaks

How do you drain/fill with no drain holes? I have a 12 bolt diff and I’m pretty sure it’s what’s making that horrible clacking sound...found a small bend at the bottom of the diff where the fluid is slowly seeping out.

[weq92f]

.
My 8+ inch 12 bolt only held 1 and a quarter quart using a stock stamped cover.

-klb

[72c20customcamper]

Originally Posted by Siedl

How do you drain/fill with no drain holes? I have a 12 bolt diff and I’m pretty sure it’s what’s making that horrible clacking sound...found a small bend at the bottom of the diff where the fluid is slowly seeping out.

No drain hole . You drain it by removing the cover the fill is on the front side in the webbing. Just a pipe thread plug . Fill till it starts coming out .

When I replaced the Chevelle 12 bolt with a 9 inch. I had a new fill added and a drain plug drain plug is protected by the fing on the bottom . I added the one picture that looks like its chrome just cause I like it

[Stocker]

Originally Posted by Siedl

How do you drain/fill with no drain holes? I have a 12 bolt diff and I’m pretty sure it’s what’s making that horrible clacking sound...found a small bend at the bottom of the diff where the fluid is slowly seeping out.

You have a fill hole though, right? Remove the cover to drain the diff.

[Steeveedee]

Originally Posted by Siedl

How do you drain/fill with no drain holes? I have a 12 bolt diff and I’m pretty sure it’s what’s making that horrible clacking sound...found a small bend at the bottom of the diff where the fluid is slowly seeping out.

Make sure that you can get the fill plug out before you drain the gear oil! If it is stripped, your truck will be immobilized until you can get it out.

A clacking noise will probably be a u-joint.

[dukcaln]

thanks guys got it all done....

[craig7070]

Do you put the new cover on almost all the way they add oil if you have the 12Bolt?

[Bigdav160]

There is fill plug on the pinion side. Takes a 3/8 square drive to remove.

Synthetic gear oil in the rear axle is a perfect application.

[craig7070]

Originally Posted by Bigdav160

There is fill plug on the pinion side. Takes a 3/8 square drive to remove.

Synthetic gear oil in the rear axle is a perfect application.

Thanks Bigdav160

[NCBowtie]

YMMV but I haven't had any luck keeping it from leaking unless I let it set up overnight before I fill it up.

[Tx Firefighter]

A new FelPro cover gasket is cheaper than a tube of silicone. It's also quicker and looks more sanitary than silicone does.
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[Stocker]

If you decide to use silicone anyway..... use this stuff, it's made for gear oil.

[dmjlambert]

Hold on to your rusty one, an aftermarket one will not be as good. I took mine off when I drained it to refill with new oil. While it was off I cleaned it up and painted the outside, and stuck the bolts through a piece of cardboard and painted the bolt heads. The inside was very nice with no rust due to being constantly exposed to oil. I used a POR-15 starter kit from Amazon.com, it was quite inexpensive and the whole job just took a couple teaspoons of paint. A little goes a long way with POR15. Do not get POR15 on anything you don't want painted permanently, such as your hands. It will not come off. Make sure the lid and top lip of the paint can are perfectly clean when you re-close the can, or the lid will not come off again the next time you have a little rust-proofing project. Dip into the can with a plastic spoon and transfer the paint to a disposable container such as a pie tin, so you don't contaminate the paint. This gives you an excuse to start the job by eating pie.

[Siedl]

Originally Posted by dmjlambert

Hold on to your rusty one, an aftermarket one will not be as good. I took mine off when I drained it to refill with new oil. While it was off I cleaned it up and painted the outside, and stuck the bolts through a piece of cardboard and painted the bolt heads. The inside was very nice with no rust due to being constantly exposed to oil. I used a POR-15 starter kit from Amazon.com, it was quite inexpensive and the whole job just took a couple teaspoons of paint. A little goes a long way with POR15. Do not get POR15 on anything you don't want painted permanently, such as your hands. It will not come off. Make sure the lid and top lip of the paint can are perfectly clean when you re-close the can, or the lid will not come off again the next time you have a little rust-proofing project. Dip into the can with a plastic spoon and transfer the paint to a disposable container such as a pie tin, so you don't contaminate the paint. This gives you an excuse to start the job by eating pie.

You had me at “pie”. Yum
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