Your Opinion on Changing DIfferential Fluids

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My first questions will involve my my 4WD 4Runner and AWD GX470. I have the owner's manuals and they say under "Severe Conditions" to change the front and rear diff and transfer case at 30K. No recommendation for "Normal Conditions." I might tow a trailer with a lawnmower twice a year at most. How often would you change the fluids? I am using synthetic (Amsoil) fluids.

Next question, there is no recommendation in the owner's manual for my cars. Your thoughts?

Amsoil says to go 50K severe service and 100K normal service.

I'm thinking 50K in my SUV's and 100K in my cars. OR would you cut it back to 30K in SUV's and 50K in cars?
 
I do all my Nissan Fluids between 30 and 50K - but there super easy - they all have a plug, no pulling the diff cover.

If yours don't have plugs I would consider getting one if there available aftermarket. Not only is it easier, you don't have to worry about the diff cover leaking or wait for the ATV to set up to put it back together.
 
Every 100k for both cars and SUVs. Nothingn you have, as described, is severe service in nature.
Diff fluid doesn't really get contaminated like engine oils do. There are no combustion byproducts, and as long as the axle is not submerged in water, there's very little moisture.

I'm a fan of an early diff fluid change, to flush out the break-in stuff, and then every 100k miles thereafter.
 
My first questions will involve my my 4WD 4Runner and AWD GX470. I have the owner's manuals and they say under "Severe Conditions" to change the front and rear diff and transfer case at 30K. No recommendation for "Normal Conditions." I might tow a trailer with a lawnmower twice a year at most. How often would you change the fluids? I am using synthetic (Amsoil) fluids.

Next question, there is no recommendation in the owner's manual for my cars. Your thoughts?

Amsoil says to go 50K severe service and 100K normal service.

I'm thinking 50K in my SUV's and 100K in my cars. OR would you cut it back to 30K in SUV's and 50K in cars?
I do 50k for all my cars with Amsoil or equivalent, or in the alternative every time the diff goes under water (a real possibility with a 4 Runner...)

Get a diff cover with a drain plug and you are good to go... if you have to take the cover off for whatever reason, use a LubeLocker gasket when putting it back together...
 
With my 17 Ram - New - I drained the initial OEM gear oil @ 15K mile mark - after towing our 12Klb 5th Wheel for over 6K miles.
The drained gear oil contained a small amount of shiny metal glitter within it. (Magnet showed it was metal)

Replaced OEM cover with much larger PPE w/drain plug (for future quick easy service) - Refilled with Mobil Delvac 1 75W-90.
Due to the towing of the 12Klb RV will continue - I will drain and refill ever 45K miles.
Front differential will be drained and refilled at that time as well.

My Opinion - You can easily go well past 60K miles - like posted above - if submerged in water in any way - I would definitely drain and refill shortly after.
 
All my diffs are easy to drain and fill. Hardest part is getting the cars level.
I just crawl under the SUV’s
 
All my diffs are easy to drain and fill. Hardest part is getting the cars level.
I just crawl under the SUV’s
I would do it at 50-60k miles. I can't see doing it sooner for normal driving conditions.
 
All my diffs are easy to drain and fill. Hardest part is getting the cars level.
I just crawl under the SUV’s
So long as there’s room for a pan, buy a fluid pump. I tried to replace gear oil in a Subaru from the bottle once and realized how dumb that was.

Just make sure to test the pump before you drain the diff! I check by pumping from the bottle back to itself.

Jack up
Loosen fill plug before you touch the drain plug (they seize sometimes)
Open drain plug (only if fill plug can be loosened)
Lower

When done draining:

Jack up
Install drain plug
Remove fill plug
Insert tube from fluid pump
Lower
Fill
Jack up
Install fill plug
Lower
Done
 
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I changed my RAM 3500 3x in 200k and seemed fine.
The Dana 70HD had 60k but was 50 year old OEM fluid; about 2/3 drained and I scooped the last 1/3 out with a paint stick and degreaser...
 
So long as there’s room for a pan, buy a fluid pump. I tried to replace gear oil in a Subaru from the bottle once and realized how dumb that was.

Just make sure to test the pump before you drain the diff! I check by pumping from the bottle back to itself.

Jack up
Open drain plug
Lower

When done draining:

Jack up
Insert tube from fluid pump
Lower
Fill
Jack up
Install plug
Lower
Done
I would insert “loosen fill plug” before “open drain plug”.

Too many mechanics have found themselves with an empty differential and a stuck fill plug.

Not good…
 
I would insert “loosen fill plug” before “open drain plug”.

Too many mechanics have found themselves with an empty differential and a stuck fill plug.

Not good…
Yep. Been there twice (I'm a dummy) and have resorted to filling through the axle tube with one side jacked up and also through the speed sensor hole.
 
With nearly every differential I have had, a change at 10K-15K would remove all of the break-in metals and I would be able to sample at 75K or so and make a decision on future changes.

This has not been the case with the axles under my Wrangler that generates more metal than any I have ever seen and I change it fairly frequently.

I would say (despite the thoughts of some) that gear oil is cheap enough and is such a low volume needed that changing it as often as you like is not going break your wallet.
 
Do first change early as it was mentioned before, may be at 10-20k miles to remove all the initial abrasive material suspended in oil.
Transfer case will need more often changes after that and with good fluid I'd say - 30-50k miles should be more than sufficient.
Rear diff - every 50-80k miles. That will keep them very healthy.
 
Don't care what Toyota or Amsoil recommends. You change it whenever you want.

30k is plenty for all my vehicles, but will also depend on calendar time, local weather, and your future expectations for the vehicle.

I also check the cold gear oil level regular, top off as needed, and can run a little longer if commute ends up longer and non-stressed.

I don't think that I'd ever go over 50k or 5 years, since all my vehicles are for long term ownership. 30k is for the tow/workhorse and for the modded vehicles that get overly spirited driving.
 
For normal use I would do differential service every 60-80k miles with a high quality lube. Cheap lubricants should be changed more often or simply not used at all.
 
If you have a magnet inside your diff, you should be pulling the cover. If very little is on it, and you have a drain plug, you can make up your own interval for fluid changes.

You can be as anal retentive as you like. Diff fluid changes are no longer a required maintenance procedure on Chevy trucks.

I purchased my 3/4 ton Suburban new in 2008. I had the dealer do the diffs in 2013, I did them in 2018 and I’ll do them again this year. The average mileage was 10,000 miles per year. I also did extra changes of the front diff and transfer case because it’s so easy since they have drain plugs.
 
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What kinds of joints on those trucks?

If like the real (90s and before?) FJ land cruisers, there is a potential for a lot of grease to get into the diff oil.
 
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