Rear Differential (RDU) fluid change

[flymore]

Is there a drain plug on the 2018 RDU?  My 2018 PTU has a drain plug. Did they put a drain plug on the RDU in 2018?

 

Videos on the subject show a pump out by hand from the fill plug and not getting all the old fluid out.

 

Thanks

 

[1004ron]

There isn't one on my 2017 and don't expect one on the 2018.

 

 

[Haz]

2015-2018 Edge Workshop Manual - Rear Differential Unit (RDU) - Filler Plug ONLY

 

 

 

 

2019-2024 Edge Workshop Manual - Rear Drive Unit (RDU) - Filler Plug

 

 

 

2019-2024 Edge Workshop Manual - Rear Drive Unit (RDU) - Drain Plug

 

 

 

 

2007-2014 Edge Workshop Manual - Rear Differential Unit (RDU) - Filler Plug ONLY

 

Good luck!

 

 

Edited March 10, 2025 by Haz

[1004ron]

This is what I use for extracting the RDU oil.

 

I made the shepherds hook/candy cane with a wire coat hanger inside some silicone tubing, used with my BMW oil extractor.

 

[flymore]

Ok, that's what I was looking for.

 

Hoping the fluid change will prevent a RDU failure.

 

Thanks

 

 

[STBEAST]

Just curious to know what fluid is used in the RDU and is there a better aftermarket alternative. I plan on doing mine soon.

Also the same question for the PTU. 

I think they are different fluids???

[Biker]

If the RDU fluid is the same as my 2019, you may want to sit down before you see the price. Thankfully it doesn't take much. 

It was different than the PTU fluid for my 2019.

[flymore]

On 3/7/2025 at 9:13 AM, 1004ron said:

This is what I use for extracting the RDU oil.

 

I made the shepherds hook/candy cane with a wire coat hanger inside some silicone tubing, used with my BMW oil extractor.

 

 

 

 

 

Not sure what diameter of silicone tube you're using, the only tube I could get to fit was 1/4 inch. The RDU is packed tight with gears and a big one right behind the fill plug opening.

 

It took me three stores to find SAE 80w-90. Finally settled on Lucas SAE 80w-90 heavy duty gear oil. 

 

Thanks

 

[1004ron]

Had to wait until I got home to measure it.

 

Silicone Tube 5mm ID x 8mm OD 1.64' Flexible Silicone Rubber Tubing

 

I use Amsoil for the PTU and RDU.

 

Edited March 10, 2025 by 1004ron

[flymore]

That tube you used is a little bigger than what I had on-hand. Next time I'll give it a try.

 

I used AMSOL in my last PTU change and I've got Motorcraft ready for the next.

 

I was late on the RDU and wanted to get it done because there are mentions of RDU failure/replacements here and on youtube.  The fluid I took out was really bad.

 

Another thing I noticed is the rust and pitting on the exhaust pipe from my cat on back to the muffler. Isn't this supposed to be stainless?

Looks like it will fail soon and I'll need a new pipe and muffler.

 

[STBEAST]

OK. I am going to use Amsoil for both. But are they different? Which one do I use in the RDU?  PTU?    

Thanks so much guys for all your help.

[flymore]

Check your owners manual.

 

Mine says SAE 80w-90 for RDU and SAE 75w-140 for PTU

 

[Haz]

@STBEAST: From the 2022-2024 Edge Workshop Manual, including Power Transfer Unit (PTU) drain & fill procedure attached below as a PDF document...

 

Good luck!

 

 

 

 

Power Transfer Unit Draining and Filling - 2.7L EcoBoost - General Procedures - 2022-2024 Edge Workshop Manual.pdf

Edited March 11, 2025 by Haz

[1004ron]

10 hours ago, STBEAST said:

OK. I am going to use Amsoil for both. But are they different? Which one do I use in the RDU?  PTU?    

Thanks so much guys for all your help.

That depends on the Model/Year.

 

Please add your M/Y to your profile signature - Settings - Ford Edge Forum

 

Amsoil is a good brand, but there's many others as well.

[STBEAST]

Ok I have a 2024 Edge ST. For some reason I could not find it in the digital owner's manual in the vehicle, but I will check again.

Sure miss the 'old school' printed manual !

Thanks for the help

Edited March 11, 2025 by STBEAST

[Haz]

@STBEAST: 2024 Ford Edge Owner's Manual (PDF direct download link)

 

 

Good luck!

 

[1004ron]

I find the electronic/digital version way more useful mainly for the word search, and don't need my reading glasses.

[STBEAST]

Thank you Haz! Much appreciated.  Jim

Edited March 12, 2025 by STBEAST

[drm1harley]

My 2020 Edge ST with 68,xxx miles began to make an inconsistent vibration sound, not feel, from the rear of the vehicle when I made a slow turn to the right from a stop. I researched potential causes and ruled out everything except the RDU. Like others who experienced similar, I went with an RDU fluid change to see if that made a difference. 

 

When I changed the fluid, the amount drained was lower than I expected, and when I filled it, I used less than the manual specs.  I had the vehicle raised on four jack stands and ensured it was level, which it was from three different locations. It’s a super easy process, draining and filling.

 

Approximately 20 oz of fluid was drained over 15 minutes, as shown in the water bottles. Not much sludge on the drain magnet, and no metal fragments were present.  When I went to refill, I could only get 25 – 26 oz before the fill hole started running out. I guess it's no big deal because once it spills out, it's full.

 

Has anyone else experienced lower-than-expected fluid when you drained the RDU?

 

As for the vibration sound….not hearing it now.  Maybe once the fluid level gets too low the vibration sound starts.

 

 

Edited September 16, 2025 by drm1harley
Attachment failed

[Jetboy47]

drm1harley: I had less fluid than expected in my RDU as well, the amount you mentioned is close to what I experienced. I also put more fluid in than took out in my PTU. My RDU needed changing at 20k. I feel much better that it is done. I bought the vehicle at 18k. I will probably change both as well as a transmission drain (approx. 5 quarts) every 10k from now on for my own peace of mind.