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Discussion Starter · #1 ·
I haven't changed out my diff fluids or transfer case. I'm almost at 60K and don't tow.
Would it be a bad thing to switch to synthetic fluid at this point or stay conventional ?
I have ben told you shouldn't change over to synthetic oil and a certain point for the engine because of the seals but didn't know if it was the same with the diff fluids. I switched over to synthetic motor oil at my first oil change but never touched the differential fluids

Thanks for any advice
 

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Pretty sure it already has synthetic, or at least a blend in it.

You can switch to synthetic, and that is what I would use, and always have used in the past.

Royal Purple, Redline, or Amsoil for the last truck, and that is what my 17 will get when it is time too.
 

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I would go synthetic. It's probably already a synthetic or synthetic blend anyway.

Personally, I used AMSOIL for the front and rear differentials. I did it at 25,000 miles (no towing, just wanted to get the initial fill out). I found a bit of iron "paste" on the drain plug magnets, but nothing worrisome. The new AMSOIL bag is much easier to use than a bottle. I also have a fluid pump from AMSOIL that makes filling much simpler.

That said, any of the name brands would be good. They all make good oils. The Mobil 1 is about $11/quart at my local parts store. A good price.

Now, I don't know what year you've got, but the transfer case in mine requires a 75W. That's an odd spec. I think it applies to 2014 and up. Blame Borg-Warner. Toyota wanted $75/quart for the stuff. 1.5 QT needed. Ouch.

I bought Ravenol 75W from a European car parts supplier for $16/Quart. Synthetic. Made in Germany for manual transmissions. Fuchs makes a similar product.

I also bought a magnetic drain plug for the transfer case. And the oil pan. Toyota put magnetic plugs in the differentials, and on every car I've had with magnetic fluid plugs, there is always a bit of "paste" to be wiped off at the fluid change.
 

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Definitely change the rear diff oil and use synthetic. The old "stick with one old to avoid problems" is an old "wives tale". I used Redline. 75-85w and they have a heck of deal per quart on it here....

https://www.rvautoparts.com/50104-Red-Line-Oil-Gear-Oil-Single_p_387665.html?

Front can go longer but change it. I may never change the transfer case oil again. It was virtually clear when I drained mine. I have a 14 with the first year of the new case from Borg.
 

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I would go synthetic. It's probably already a synthetic or synthetic blend anyway.

Personally, I used AMSOIL for the front and rear differentials. I did it at 25,000 miles (no towing, just wanted to get the initial fill out). I found a bit of iron "paste" on the drain plug magnets, but nothing worrisome. The new AMSOIL bag is much easier to use than a bottle. I also have a fluid pump from AMSOIL that makes filling much simpler.

That said, any of the name brands would be good. They all make good oils. The Mobil 1 is about $11/quart at my local parts store. A good price.

Now, I don't know what year you've got, but the transfer case in mine requires a 75W. That's an odd spec. I think it applies to 2014 and up. Blame Borg-Warner. Toyota wanted $75/quart for the stuff. 1.5 QT needed. Ouch.

I bought Ravenol 75W from a European car parts supplier for $16/Quart. Synthetic. Made in Germany for manual transmissions. Fuchs makes a similar product.

I also bought a magnetic drain plug for the transfer case. And the oil pan. Toyota put magnetic plugs in the differentials, and on every car I've had with magnetic fluid plugs, there is always a bit of "paste" to be wiped off at the fluid change.
The "paste" is TFE paste used to seal the pipe threads on the drain and fill plug of the transfer case and to act as anti-seize.
 

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The "paste" is TFE paste used to seal the pipe threads on the drain and fill plug of the transfer case and to act as anti-seize.
No. It isn't.

I know what thread sealant looks like.

I used the word iron and then "paste" in quotations to describe what's stuck to the drain plug magnet. It's grey/black, extremely fine, and stuck to the magnet, not the threads. It's ferrous metal that has been captured by the magnet.

In an unfiltered system, like a transfer case, or differential, that doesn't see frequent changes, capturing and removing that type of contamination will improve the operating life of the component.

I don't know what word you would use to describe it, but whatever you call it, magnetic plugs are a good idea.

That's why Toyota included them on the differential, and why I added one to the transfer case.
 

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No. It isn't.

I know what thread sealant looks like.

I used the word iron and then "paste" in quotations to describe what's stuck to the drain plug magnet. It's grey/black, extremely fine, and stuck to the magnet, not the threads. It's ferrous metal that has been captured by the magnet.

In an unfiltered system, like a transfer case, or differential, that doesn't see frequent changes, capturing and removing that type of contamination will improve the operating life of the component.

I don't know what word you would use to describe it, but whatever you call it, magnetic plugs are a good idea.

That's why Toyota included them on the differential, and why I added one to the transfer case.
Sorry for the misunderstanding about what "paste" you're referencing.

There is white TFE paste on the Borg drain plugs and they are pipe threads. Borg has been using them for years like this for many different models and manufactures. Just want to make sure people don't remove it without adding some back.
 

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Yes.

Thanks.

I did use a dab of fresh PTFE on the threads when I changed the fluid. For those considering the job, a PTFE lubricated NPT plug doesn't take a lot of torque to seal properly. Be modest in putting it back in.

And I found out that the drain plug was in fact NPT (Pipe Thread). I used this one from Amazon for the transfer case, if anyone is interested.

https://www.amazon.com/gp/product/B002A35ER4/ref=oh_aui_search_asin_title?ie=UTF8&psc=1

Gold Plug 1/2"-14 NPT Industrial Magnetic Drain Plug (Internal Head) IP-04

Naturally, I assumed it was a metric part, because, you know, Toyota, and ordered a metric size (judging/estimating from the outside) in preparation, only to find out it was NPT when I removed the OEM one...

C'est la vie...

And while you can use a 3/8" socket extension to turn the plug, a proper pipe plug tool fits more securely... I bought this set:

https://www.amazon.com/gp/product/B002GTA2F6/ref=ppx_yo_dt_b_asin_title_o03__o00_s00?ie=UTF8&psc=1
 

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Discussion Starter · #11 ·
I did the rear diff this evening, for 60K miles it looked pretty good, nothing on the magnet I think I could have easily gotten another 60k out of it LOL. Went with Valvoline Synthetic since Advanced Auto didn't have anything else in stock. Might try Mobil or Royal for the front and transfer case. Hopefully the front change will go as well. Did need the breaker bar to take the bolts off hopefully the front wont be as bad since I think those are only supposed to be around 40#s of torque
 

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Toyota does not recommend replacing the fluid in the front or rear differential at any mileage. Same for my Chevy heavy duty diesel truck where fluid only is changed if repairs are made to the unit. I would expect that a synthetic lubricant is used in the differential from the factory.

Not much happens at the differential to reduce the effectiveness of the fluid. There is no fuel contamination as with the motor oil and no heat as with the transmission. Even with my diesel truck's Allison transmission, if I use TES 295 ATF the change interval is every 150,000 miles or 48 months, whichever occurs sooner. This is with a truck that is tow rated at 17,300 pounds.

If I was replacing the differential fluid after a repair then I would use synthetic as it will not need to be changed again for the life of the truck.

I tend to RTFM and make a cheat sheet that provides me with a service interval schedule for my vehicles and keep a copy in the glove box along with any key specifications for lubricants and filters if applicable. In the long run it saves me time.
 

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Toyota does not recommend replacing the fluid in the front or rear differential at any mileage. Same for my Chevy heavy duty diesel truck where fluid only is changed if repairs are made to the unit. I would expect that a synthetic lubricant is used in the differential from the factory.
Umm...they DO recommend replacing it, a lot. Check your maintenance manual.
 

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I dunno, gm does suggest to change the trans fluid in a duramax equipped truck at 60k. I just searched for the document, because I remembered it being called for way sooner than that. Old d-max trucks had issues with trans's before 150k. Same with t-case issues from a hole getting rubbed somewhere, there was an update kit you could buy for it.


I just know that the rear diff on my FJ at 20k, was dark, a lot of metallic debris (meaning the metallic paste) stuck to the magnet.
My 2010 Tundra at 20k, same thing. Fluid wasn't burn't like old gear lube. But it still could have used changing. Wasn't clean.

The T-case was clean on the FJ at 35k, front diff was dark. My Tundra I didn't change the front diff, it was done when the rack was replaced.

But... When I look at my 2003 3/4 GM, the T-case was full of metal shavings at 24-30k. Of course, was told it isn't broken yet, so we can't fix it.


I am rambling. I mean. Guy asked about what fluid to use, then GM trucks get tossed in, so I figured why not.


Point is: Diffs and T-cases are subject to the same manufacturing debris as the engine. They have no filters, other than a plug. Why not change it, and use the best you can?

I haven't put more than 50k on a vehicle. Period. I still do these things.


In life we do things not because it is necessary, but as a preventative measure.

Like wiping down a shopping cart while getting groceries. You are about to touch things on a shelf, buttons on the card scanner, then grab a pen to sign, or use cash and get change Nothing else was wiped down, EVER... By the time you stop at fast food on th way home, you still will grab a few fresh hot fries, not even thinking about everything else... But, people wipe down shopping carts anyways.
 
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Umm...they DO recommend replacing it, a lot. Check your maintenance manual.
What manual and on what page do you see a recommendation to replace the differential fluid with normal use? It is not in the 2018 Toyota maintenance manual. ONLY with SEVERE Duty is the differential fluid replacement specified and that means spending 90% of the time operating on dirt roads or towing a heavy load, as in more than 5,000 lbs. on an ongoing basis. Driving to work or the lumber yard or towing a ski boat on the weekends is not severe duty.

My first truck was a 1956 Willy's and it definitely needed fluids changes and seals replaced quite often. But no 4WD truck or SUV, which includes a diesel heavy duty truck that I now own, has required changing of differential fluid under normal use.
 

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Toyota does not recommend replacing the fluid in the front or rear differential at any mileage. Same for my Chevy heavy duty diesel truck where fluid only is changed if repairs are made to the unit. I would expect that a synthetic lubricant is used in the differential from the factory.

Not much happens at the differential to reduce the effectiveness of the fluid. There is no fuel contamination as with the motor oil and no heat as with the transmission. Even with my diesel truck's Allison transmission, if I use TES 295 ATF the change interval is every 150,000 miles or 48 months, whichever occurs sooner. This is with a truck that is tow rated at 17,300 pounds.

If I was replacing the differential fluid after a repair then I would use synthetic as it will not need to be changed again for the life of the truck.

I tend to RTFM and make a cheat sheet that provides me with a service interval schedule for my vehicles and keep a copy in the glove box along with any key specifications for lubricants and filters if applicable. In the long run it saves me time.
Umm...they DO recommend replacing it, a lot. Check your maintenance manual.
What manual and on what page do you see a recommendation to replace the differential fluid with normal use? It is not in the 2018 Toyota maintenance manual. ONLY with SEVERE Duty is the differential fluid replacement specified and that means spending 90% of the time operating on dirt roads or towing a heavy load, as in more than 5,000 lbs. on an ongoing basis. Driving to work or the lumber yard or towing a ski boat on the weekends is not severe duty.

My first truck was a 1956 Willy's and it definitely needed fluids changes and seals replaced quite often. But no 4WD truck or SUV, which includes a diesel heavy duty truck that I now own, has required changing of differential fluid under normal use.
Hey bud, don’t get your t*tties twisted all up. You asked where it said in the manual to change the diff fluids and were not specific to what kind of usage as in severe or normal. I simply screenshot the manual to show you that you were not correct. Now you are telling me you are the old sage mechanic with your Willy’s so I should just believe whatever old school belief you are throwing out there to everyone. Good luck sir.
 

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I'm at 44,000 miles and have two jugs of Redline 75W90 full synthetic sitting here ready to go for the front and rear diff's. Will do it at 50,000 miles. Or if a decent warm afternoon presents itself prior to that.

Have 75W Ravenol full synthetic on the way for the transfer case.
 

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I'm at 44,000 miles and have two jugs of Redline 75W90 full synthetic sitting here ready to go for the front and rear diff's. Will do it at 50,000 miles. Or if a decent warm afternoon presents itself prior to that.

Have 75W Ravenol full synthetic on the way for the transfer case.
I’ve been running that 75W Ravenol for about 6k miles in the TCase with no issues. Sure beats paying what Toyota wants for their fluid. The bottle it comes in is...ummmm...unique.
 

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I’ve been running that 75W Ravenol for about 6k miles in the TCase with no issues. Sure beats paying what Toyota wants for their fluid. The bottle it comes in is...ummmm...unique.
Mine shifts better since I changed and used the 75W Ravenol. Before, I had to shift into to neutral to get it change or it would take a while to disengage. Doesn't do it anymore. Disengages much faster. Great deal and good oil.
 

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I’ve been running that 75W Ravenol for about 6k miles in the TCase with no issues. Sure beats paying what Toyota wants for their fluid. The bottle it comes in is...ummmm...unique.
Mine shifts better since I changed and used the 75W Ravenol. Before, I had to shift into to neutral to get it change or it would take a while to disengage. Doesn't do it anymore. Disengages much faster. Great deal and good oil.
I agree with you on the quicker shifting. There has been a lot of snow lately where I am at and have used 4WD a lot lately. There is a difference.
 
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