I've used this device. Works well. You want to get a tube long enough to reach the bottom and make sure the
tube doesn't fall into the diff.

Amazon.com: Lincoln Electric Lubrication 615 20 oz. Suction Gun : Automotive

Buy Lincoln Electric Lubrication 615 20 oz. Suction Gun: Grease Guns - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

 

I've used this device. Works well. You want to get a tube long enough to reach the bottom and make sure the
tube doesn't fall into the diff.

Amazon.com: Lincoln Electric Lubrication 615 20 oz. Suction Gun : Automotive

Buy Lincoln Electric Lubrication 615 20 oz. Suction Gun: Grease Guns - Amazon.com ✓ FREE DELIVERY possible on eligible purchases

www.amazon.com

Can you tell me a little more? My current understanding is that this device can possibly be used to pull gear fluid from the diff? Just wanting to get clarification.

Very much appreciate your post because it offers an option to pulling everything apart.

Thanks

 

If the oil doesn't smell burnt, have water in it or metal flake I'd leave it. There's a reason there's no easy way to change it. It was designed to last a long long time.

 

I thinks it's like 50,000 or 5 years. Which ever comes first.
It's time for an oil change.

 

You really need to take the centre out.
Clean out the well with a rag. It will be full of sludge.
Gives you a good reason to inspect the U joints.
If it had a drain plug it would be leaking.

 

 

The rear end lube in my cars is used up by 40,000 miles / 4-5 years . If the car is seldom driven, then it’s probably going to last longer.

For cars that see hard usage, then Mobil 1 75w-140 is a good choice for keeping wear down to a minimum. For all others, Mobil 1 75w-90 works just as well.

Z

 

What's a good indicator that the oil is used up?

 

When it doesn't look like nice, new gear oil, eg. dirty, dark, metal filings, etc. A caution though.... gear oil isn't like engine oil and has no "suspension agents" in it to hold contaminants so all the "junk" will settle to the bottom of the center section as sediment which is one reason why it's a good idea to pull the chunk and clean everything.

 

I pulled my rear end cover and cleaned the gears with solvent and put everything back together with a new gasket. This pump worked great.

Amazon.com: Slippery Pete Fluid Pump for Gallon Bottles and Wide Mouth Quart Bottles (Not for Standard Quart Bottles) - Transfer Gear Oil, Transmission and Differential Fluid, Antifreeze with This 30cc Hand Pump : Automotive

It fits the top of these bottles as well as others.

Amazon.com: Ultra1Plus SAE 75W-90 Synthetic Gear Oil, API GL-5 | 1.05 QT / 1 L : Automotive

 

Got it. thanks for the reply.

 

I use those suction guns for rear axles, they work well, but take some patience. You can bend up a piece of steel fuel tubing to get down to the bottom of the housing through the fill plug, and hook the gun to it. Getting most of the old oil out is fine.

Once you get done, you can use the gun to put the new oil in. You can suck it out of the bottle or take the hose end off and pour it in, then inject it through the fill plug hole.

 

I use those suction guns for rear axles, they work well, but take some patience. You can bend up a piece of steel fuel tubing to get down to the bottom of the housing through the fill plug, and hook the gun to it. Getting most of the old oil out is fine.

Once you get done, you can use the gun to put the new oil in. You can suck it out of the bottle or take the hose end off and pour it in, then inject it through the fill plug hole.

Thanks for the input. This is one of those tasks I just know I should address.

 

I recently swapped the gear oil in my 65 daily driver. The last time the oil was changed was probably around 25 years and 30k miles ago when the previous owner restored the car. I'm glad that I pulled the 2.8 open differential as there was sludge and the axle tubes needed cleaning. I also replaced the rusted vent tube fitting. The axle bearing seals needed replacing as well. So depending on how long it has been, it might be a good idea to pull everything and do a full inspection. I ended up upgrading to a 3.0 true track anyways. On another car that was just recently restored, I used a pump to flush and put in anew fluid. The pumps are slow, so it will take a few hours, but it does save a lot of work. I use Valvoline 80-90W GL5 spec oil in my 8" and friction modifier when required.

 

The best advice in many cases will cause you to do the most work. Everything you posted seems to be the way to go. It's times like this I really wish I had a lift.

Did you have access to a lift? How long did it take?

Those who avoid work suffer

Great advice, thanks

 

As others have said I would pull it apart and inspect everything if you have the time and aren't in a hurry. Then you can add a drain plug if your handy with a welder or have one.

It's more expensive than the others mentioned but i have one of these and love it for brake fluid flushes.
I would use this If my rear axle didn't have a drain plug already. You just need a air compressor though

Capri Tools CP21029 Vacuum Brake Bleeder https://a.co/d/a3efSWR

 

As others have said I would pull it apart and inspect everything if you have the time and aren't in a hurry. Then you can add a drain plug if your handy with a welder or have one.

It's more expensive than the others mentioned but i have one of these and love it for brake fluid flushes.
I would use this If my rear axle didn't have a drain plug already. You just need a air compressor though

Capri Tools CP21029 Vacuum Brake Bleeder https://a.co/d/a3efSWR

Sounds like many are leaning towards the hard but necessary work. Thanks for the reply.

 

Not much more to tell. You stick the tube in fluid, pull back on the 't' handle, then move the tube to another container and push the 't' handle to dispose of what's in the cannister. It's a slow process, as Hemikiller indicated

 

Got it for sure. I have no idea how thick the gear oil is in my diff. If it's thick sludge I may be in trouble.

Was the gear oil you pulled out very thick?

 

80-90w

 

Thanks

 

Comparative graph of oil viscosity types, including SAE Engine oil and SAE Gear oil. You can see that gear oil is rated differently, and surprisingly in the same range or slightly thicker than engine oils:

 

I don't think they were figuring on 56 years!!!

 

Of course not.

 

I just did this on my 64.5 289 convert that I have owned since 1967, 92,000 miles, first time changed.
Supported on jack stands, but not on the differential since muffler would have been in the way of the fill plug.
Used an $8 harbor freight hand suction pump through the fill plug hole. Oil was black but not sludge. You don't have to remove every drop, 95% new oil will give excellent lubrication. Pumped in new oil with same pump.
Didn't drip before, still doesn't drip.

 

Drain warm if you can. I like overnight after a drive, park and pull the plug. Then see how much came out.
But .. the best advice I've got was "look and see" if you haven't done a full clean, and never been inside it, I recommend pulling the center and go from there.
All you get from drain and fill is you KNOW it's has new fluid. If you "look and see" you will find out and repair and then KNOW what you have driving down the road.
PS if you don't know ask, if not sent it to a pro and know it's fixed properly.
Good luck 🤞