Differentials and Transfer Case Fluid Change

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As someone who has run in many motors, transmissions and rear ends in multiple applications , whenever you have two new metal surfaces making contact you will have initial wearin and metal dispersal into the fluid and onto the magnet.

I always feel changing these fluids, and clearing those magnets allows them to do the job of capturing normal wear and tear particulars vs the initial heavier wear in metal that you see in this thread.

It's definitely optional and not required but I am still looking for those fluid specifications if anyone has, much appreciated.

Here’s a link that’ll help https://www.amsoil.com/lookup/auto-...l-engine-code-h-99h-h-turbo/?volume=us-volume

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[Amsoil guy]

Hi Tyler,

You are correct that Ford only uses products that meet their specifications and perform for the intended useful life. Maybe there are superior products out there and you are certainly free to piss away your money on them...

I agree with you as well . Tyler is correct and is definitely free to spend his money and get the most out his choice of fluids that’s worth every dollar .?

 

[createaneutron]

I plan on doing the rear differential tomorrow and wanted to confirm a few things.

The drain plug is located (if looking rear to front) on the bottom left front side. It appears to just be a 1/2in socket extension. Can someone confirm that?

After I drain, I put alittle thread tape on it and reinstall. Undo the fill plug, located to the rear of the differential. Fill until over flows. Reinstall plug.

This sound about right?

Make sure you can fill plug off FIRST!

 

[2020RangerBlack4x4]

For those who want to know every little detail for doing a rear differential fluid change.

1. Take a 3/8 5in extension, socket wrench, PB Blaster, a rag, replacement fluid, and a catch tub to the back of the truck near the spare tire.

2. (Optional) Spray PB blaster on the bolts. I did this because the extension doesn't lock in the bolt head like I thought it would and I didn't want to strip it. I also didn't know how tight the bolts were. They weren't.

3. Loosen fill plug which is on the rear middle of the differential. Very easy to loosen.

4. Loosen drain plug which is on the front driver side of the differential. Mine was very easy to loosen

5. Remove drain plug by hand to reduce the mess and clean off with a rag. I put some thread tape on the bolt and reinstalled it after it was done draining. I reinstalled by feel like I do with everything on a vehicle. I only have 8500 on the truck so I didn't feel like it was necessary to replace the bolt.

6. Clean the drain plug area so you know if it leaks.

7. Remove the fill plug.

8. Cut the bottle cap of the replacement fluid and squeeze the shit out of the bottle until you can't get anymore out cause the spare tire is in the way.

9. Grab the other quart and squeeze the shit of out that. I managed to get a Quart in doing this method.

10. Combine the fluids into 1 bottle and resqueeze the shit out of it. This got the fluid to overflow and drip out... telling me I got 1.5 QTs in the differential.

11. Reinstall fill plug and clean area.

12. Log in your record book and start your truck.. move it around some. Engage your locker and 4L. Recheck for leaks.

13. Drive happy.

 

[Big Blue]

I agree with you as well . Tyler is correct and is definitely free to spend his money and get the most out his choice of fluids that’s worth every dollar .?

Nobody has said Amsoil is not a good product. Is it the best, maybe, maybe not. I don't know and don't really care. What is so obnoxious and draws so many sarcastic comments, is the way it's fans push it like it's some kind of miracle elixir for you vehicle. Reminds me of some kind traveling medicine show selling snake oil as a wonder drug. I even think it's dealer network is some kind of pyramid setup like Mary Kay.

There I said it, let the comments rain in.

 

[dtech]

Nobody has said Amsoil is not a good product. Is it the best, maybe, maybe not. I don't know and don't really care. What is so obnoxious and draws so many sarcastic comments, is the way it's fans push it like it's some kind of miracle elixir for you vehicle. Reminds me of some kind traveling medicine show selling snake oil as a wonder drug. I even think it's dealer network is some kind of pyramid setup like Mary Kay.

There I said it, let the comments rain in.

Here is a link to BITOG where an Amsoil rep is involved in a discussion defending the "superiority" of Amsoil products, the rep admits that they are a "blender" and use Exxon Mobil to purchase many of their base lubricants and then blend in additives.

In some ways reminds me of Microsoft, who did a great job of brainwashing (aka training) their reps to pitch that every one of their products was the best on the market, only a limited amount of customers, generally those with limited technical expertise bought into MS pitches, some products yes very good while others not even near to be the best on the market.

https://bobistheoilguy.com/forums/threads/amsoil-whats-the-difference.332148/

 

[bd377103]

I just changed the rear diff fluid on my 21' with 300 miles on it. I found about 4 shavings 5cm in length and the rest of the fluid was flaky as I expected, nothing alarming in my opinion. The magnet on the drain plug is what I would consider saturated and no longer able to absorb any additional material.

I was only able to drain about 1.25L out of the factory fill which I consider under filled for a non locking diff according to Ford's written spec.

 

[machinist85]

I changed mine at 1,000 miles and it drained almost 2 quarts. Oil was dark but no visible shavings. Just a fine paste on the magnet.

 

[THLONE]

I wouldnt worry too much about it unless you want to.

 

[Leftcoast]

I rebuilt my whole motor at 100 miles. You can never be too sure.

 

[ryyck]

I just changed the rear diff fluid on my 21' with 300 miles on it. I found about 4 shavings 5cm in length and the rest of the fluid was flaky as I expected, nothing alarming in my opinion. The magnet on the drain plug is what I would consider saturated and no longer able to absorb any additional material.

I was only able to drain about 1.25L out of the factory fill which I consider under filled for a non locking diff according to Ford's written spec.

You got Ford's best.
I changed mine at 2k and found nothing relevant. The fill is relative to the day.
Hopefully the next change is leaner. Take care of your truck. Ford tosses them out like candy in a parade.

 

[Trigganometry]

My old Ranger a 97 with 289K had the factory fluid in the pumpkin when I retired it. No leaks and ran nicely over the 23 years of service.

300 eh…

 

[Trigganometry]

with 12 years experience of setting up bevel gear patterns for proper meshing, I feel that if a gear pattern is set poorly, youre heading for a failure at some point.
how fast that happens depends on how poorly the setup was.

the slivers of metal from the edges of the gears, or the bearing cages can happen, but the machining process' have come a long way over the years and are rare these days.

a sliver if you get one, can get crushed between bearing faces, or gear faces and cause dents that may further break down. generally anything that can be seen and felt with a 0.2mm ball tip is reason to be concerned. anything else likely wont progress to a failure unless you're really pushing the power through it.

when the gearset is set incorrectly, the gear faces slide together instead of push off from one another. the oil loses its ability to provide a protective layer between the gears.
this causes micro pitting to form and subsequently will start spalling.
micro pitting looks like frost on the gear contact patterns. it will darken your oil as the material worn off is small and creates a paste on a magnet, and can also look like a shimmer in the oil.
when the spalling starts, you actually lose flakes of metal as the contact patch really starts to tear itself apart. this further damages the gears and bearings and the life will be cut down significantly

changing your oil at 300 miles wont save you from this type of failure.
about the only benefits would be running an oil sample to see if the gear wear is showing up in higher concentrations
perhaps a re-adjustment will save the gears if you find it early enough.

There is another thing happening in the mesh zone during operation. There is a hydroscopic layer of fluid between the theoretical contact points. Thin as it may be it keeps wear and friction at bay. It happens naturally and even with extreme pressures will remain. When fluid gets aerated it disturbs this from happening. If surfaces don't line up correctly as you pointed out this also is detrimental breaking down the intended operation.

I learned this all from an old timer years ago. He was a genius in fluid dynamics and hydraulics. They use to design massive machine bearings that were solid cones that ran on a hydroscopic layer of hydraulic fluid at 7 psi. Those were built 65 years ago and still in operation today on centerless grinders.

 

[Tom_C]

I checked the manual and I didn't see it, but when should we check/change the diff? Can't see myself doing it at 1k

 

[JJG]

I change my damper every spring, because the fall drops winter on me really hard. ?‍?️

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