1. Richard Reau

    Richard Reau Member

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    Hello Gents, I just got a 4-post lift in my "compound" and so far it is awesome. I bought it gently-used off FB Marketplace for $1800, and did the install myself with the help of my lovely wife. Now that I'm under the car, I'm cleaning underneath, marveling at how clean the car is for an Ohio car, (only light surface rust underneath) and thinking about changing out the differential oil.

    So, any recommendations on changing the gear oil? Should I suck out the old stuff, or simply top off what's in there? Which product should I use?

    Thanks guys, as usual, for your great advice

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  2. Keith926

    Keith926 New Member

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    I ran into the same exhaust tips as yours on a 64 Cadillac, I would check the fluid and see how it looks for wear and go from there, it's not a big deal to remove the pan and change it, sucking it out isn't effective use of one's time vs pulling the pan, congrats on the lift, they are like a pocket on a shirt
     
  3. CBODY67

    CBODY67 Old Man with a Hat

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    You can just top it off, if needed and go from there. With no "pan" on an 8.75" Chrysler rear axle, extracting the fluid is the only way, other than pulling the center section out. If you do change it, use just normal 90W or 80-90weight rear axle grease. Check the FSM for the correct GL spec, for good measure. They got along just fine with the normal rear axle lube, well before any syn lube was available for them.

    Have fun!
    CBODY67
     
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  4. Big_John

    Big_John Illegitimi non carborundum FCBO Gold Member

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    There are always questions that should be asked before blindly giving advice... and the intrawebs is getting more famous for just tossing some answers out there.

    First, is the level down? You mention "topping it off". That tells me either a leaking seal or gasket. Gasket is kinda not a huge deal, other than it's not going to get better, and same for the seal at the pinion. But if it's an axle seal, then you are ruining rear brake shoes and it needs to be addressed. These are symptoms of a problem and "topping it off" just means putting off the problem until it gets worse.

    Second, since you ask for recommendations, does the car have a sure grip rear end? Chances are not, but the choices of gear oil will change if it's an open rear or it needs the friction additive for the sure grip clutches.

    If it were me, I'd check the level, and if it's good, probably leave it alone. All the gunk settles to the bottom and you'll never suck it out, so I don't know if there's much to be gained by changing it. It won't hurt though. If it's a sure grip, and I wanted to change the fluid, I'd be tempted to pull the center section and clean everything out a bit better for a fluid change, but that's just me being a little bit anal about it and chances are it really doesn't matter.
     
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  5. jcslocum

    jcslocum Member

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    As Big John says; check for leaks.

    I would vacuum it out and replace with the right oil. That could be 40 year old oil in there and fresh new oil mat save you from problems. It's the right thing to do!! And a great use of you new lift. Congrats on that. I have a 2 post and it's the best tooling investment I have ever made.
     
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  6. 3C's & a D?

    3C's & a D? Senior Member

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    Well said! It seems as though everyone is assuming it is a Chrysler 8 3/4 rear end, which is understandable, as it is the most common rear end on our beloved C's. However I see a Riviera in the background, and I'm not sure, but the red car looks like a '65 Buick special? Or wildcat?

    I always like to suck out the old oil and replace with new. It's one of those things few people follow regarding routine maintenance. Be sure to get the oil nice and warm before sucking it out. I like to do it again after a thousand or two miles, as you're never going to get all of the old oil out the first time. If the oil doesn't have the nasty burnt smell, one change should be good.

    Edit- I just looked at the avatar photo, clearly it is a Chrysler fastback, Newport? It's always good to include details such as what car you are asking questions about in each thread.
     
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  7. 68 4spd Fury

    68 4spd Fury Well-Known Member

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    I'll add one more thing, check the seals after. I had mine changed not long after the initial purchase and it was the original oil. It must have been down some since it started leaking out the seals that must have dried out. The outers are fairly simple to change but I had to do one inner and had to take that shaft to a shop. Congrats on the lift too! What is the inside height of your compound? Looks like an 8' high door, maybe 4' above that? Curious, I'm looking at building one now.
     
    Last edited: Mar 23, 2021
  8. stubs300

    stubs300 Senior Member

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    Nice lift, I dig the Buick! If the axles never been flooded, you're good! If the axles not covered in gunk, chances are good you're not leaking badly. Pull the plug, if oil oozzzs out, you're full. If not just squirt some in and top it off the it comes out and call it good. Weather not not you want to drain and replace it is your call, it's your car but not needed unless the rear has been abused/neglected. Good Luck
     
  9. 413

    413 Well-Known Member

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    Change the oil in that axle, it is a good thing. Run it till warm then Suck it out, it mixes all the bad stuff in the oil and warm oil is easier to remove.

    don’t fill it until it comes out, that is too much. If you have ever filled a dry one with the specified amount of oil it doesn’t run out the hole. Too much oil can foam up and come out the vent.
     
  10. Richard Reau

    Richard Reau Member

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    Thanks fellas for your widely-varying responses. It just seems to me that the oil could be 50 years old, and so...why wouldn't you replace 50-year-old oil? It is baffling that the engineers didn't put a drain plug at the bottom of the differential, like at the engine oil pan.

    But no, the thing isn't leaking, has never been in a flood. And I'm with STUBS....fill it until it comes out of the hole....otherwise how you gonna know how much is in there?

    Regarding the lift: My ceiling is 13 feet, so that allows me to raise the Riviera (or Newport) up high enough that the lift runways are at about 6'6". That is more clearance than I need to easily walk under the thing, and more than I need to work underneath.
    I will need to raise up the 7' door so that I can lift a car and also store another car under it. An that's the plan, to get another car to store under it! It's a disease as I'm sure you're all aware.

    Cheers and thanks again for the help......Rich in Tampa
     
  11. 413

    413 Well-Known Member

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    I worked at the dealership, they tell you nicely to not fill them till it runs out the hole, if you keep doing it they get a little more aggressive with the talk.
    They are over full that point and they can leak. The oil comes out the vent. The customer is not happy. So then you get to work on it for free. You learn really fast that way! Right in the paycheck. If you did it right it wouldn’t be back again.

    Put some oil in, insert finger and see where you are. with the level. STOP before it’s to the fill hole.

    I type this stuff to help you folks not to exercise my fingers.
     
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  12. stubs300

    stubs300 Senior Member

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    Well, excuse me for living!
     
  13. '66 Fury I

    '66 Fury I Member

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    So, does this advise apply to manual transmissions as well?
     
  14. 413

    413 Well-Known Member

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    Yes every gearbox like that where there is no dipstick.

    I bought a 67 mopar with power steering and the seller said it leaked PS fluid. When I saw the car he had the fluid filled up to the top of the neck! He said it keeps going down so he refill is it! Well when it gets hot it expands and comes out, And when you drive on hills or hit the brakes it’s going to come out.

    This is over the top example but it’s a real example and something people think that more is better. It’s not.
     
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  15. 413

    413 Well-Known Member

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    No not that rash at all. Your living just fine!

    Just saying Im’m not making this up, I lived a life of auto service & repair and a person learns a lot of things doing that job for 2000 hours a year for many years.