AT/DIFF/Transfer Case Fluid Changes

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I can relate to the obsessive ways a lot of us have with our cars and trucks when it comes to fluid changes. On another forum, I've noticed some people are big on changing the differential, transfer case and transmission fluids very early on their trucks. With the engine oil I can see the reason, but not so much with the other fluids. Do you agree? I believe the intervals are 30k for severe service on my truck.
 
To me swapping out all the fluids for a good quality synthetic is a good thing. Think about most manufactures and the fluids they use. To me the lowest bidder gets the contract and the fluid just has to meet the minimal spec's.

Look at GM and all the issue with their 8sp in the pickups. GM even went as far as to reformulate the dexron hp fluid in hopes it fixes the issues. I have read on some GM forums that a few have used AMSOIL's ATL fluid and it actually fixed the issues with the transmission.
 
I'm pretty sure I know what forum you're talking about (used to be a member when I had my 2nd gen Frontier) and they're a little too fanatical about that stuff. Pretty sure if you do the severe service intervals you'll be good. How many trucks go hundreds of thousands of miles without even servicing those items. As long as you're not going into deep water often, you're good.
 
Since Supertech is cheap and there are often sales, I went ahead and changed my rear diff fluid at 16k. I also did the transfer case because I found Napa ATF+4 on the cheap, too. I did the front diff and transmission (also ATF+4) at 20k. I'll probably do them all again at 45k and every 25k after that. I do tow and do a bit of off-roading, so why not.

On my JK I've used Supertech full syn in the diffs, Pennzoil or Valvoline Synchromesh in the tranny, and Castrol or Napa ATF+4 in the T-case every 25 to 35k and all is well at over 140k miles. I think I did them early, too, way back when it was new. Probably 20k miles.

Is it necessary? No. But it makes me feel better and maintaining the Jeeps is as much a hobby as it is a necessity.
 
Personally I change the ATF in my truck every 10k but thats because the A4LD is notorious for overheating itsself and I have a big supply of Dex/Merc stocked up and that's my main application. By way of differential its more so gear oil is cheap and if you're towing consistently it is definitely worth doing. Or using 4x4 often or have an AWD vehicle same idea with the transfer case. The train of thought being that the manufacturers are shorting the amount of maintenance you need to do to advertise lower cost of ownership and to keep the vehicle from lasting as long as it physically can so that you will buy another one.

With that being said I don't really have a whole lot of experience by way of that actually helping.
 
I haven't owned a new vehicle in 10 years, but on every used vehicle I buy I always swap all the fluids. On a new vehicle, I would personally swap the diffs, t-case, and tranny at around 5k to remove any wear particles from the gears getting friendly, and then go on the manufacturer's recommended change interval for everything but ATF, which would be every 50k whether it needs it or not.

On Subies I buy or service, diffs & manual trans always get Motul Gear 300, 4EATs get MaxLife ATF, and the engine usually gets something out of a yellow bottle. But lately I've stockpiled a bunch of Rotella & Delo 10W30s, and Motul 5W30, which works in almost any Subaru.
 
How many "early changers" there are overall vs. the number who post on these boards? is one question.

You ask if we agree with your seeing a reason to change engine oil early but not so much with the other fluids? How could we not?

I just bought a 2005 vehicle which had fewer than 48K. The PO had 16 oil changes done but no others.
The quick lube place he used states "check fluids" on every invoice.
However, the transfer case drained nowhere near its 40 ounce capacity. I'd bet it was more like 20 ounces.....20 ounces of very dark fluid

When it stops raining I'm going to change the others.
The transmission calls for 30K pan drops/filter changes. It's overdue. I'm dying to see its color!
The transfer case now clicks into and out of 4HI crisper. 4LO test to follow.
The diffs call for 100K (some say 150K) servicing but, as stated, the fluid is 15 years old so I'm changing it.
If the diffs drain horrid fluid I'll use the 80W-90 conventional fluid I bought first for cleansing then consider going to synthetic.
The coolant was never touched so draining it and running a cleaner through the system is going to happen. G-05 all the way.
I want my brake fluid flushed too.
 
By early I mean 5k miles on a new truck. Unlike engine oil, the other fluids are not exposed to the same contaminants so I don't think it's as necessary to change them.

Delta, you got it.
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I did the first transmission, transfer case, and differential fluids at 10K miles on both of my Jeeps. IMO it was worth the effort, especially considering how long I typically hold onto a vehicle. Going forward the transfer cases and transmissions will get serviced every 30K miles, and the differentials every 50K.
 
^I'll likely do the same and wait until around 10k.
 
Originally Posted by buster
^I'll likely do the same and wait until around 10k.

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I did my homework and came to the conclusion 10K was a good number for the first service. 30K was what I used for ATF service for many years so I stuck with that, and figured while the drain pan was in place the transfer case was easy enough to drain. 50K seems reasonable for differentials, after the initial 10K change.
 
For our new 2017 Explorer I had the dealer change the infamous PTU at 9,000 miles and I did a drain & fill on transmission at 12,000 miles. The factory Mercon LV was black, it looked nasty for ATF. And that ATF is supposed to be in the transmission for 150,000 miles
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! I had the rear diff fluid changed at 22,000 miles, it was black. Both the PTU and the drain and fill for the transmission are easy to do as both have drain plugs and relatively easy to access fill locations. We keep our vehicles for a lot of miles and time. spending a little more in fluids is worth it in the long run for us. As I understand the worse wear material in the fluids of these units occurs early on and once changed there is usually much less wear material debris afterwards.

Whimsey
 
There's a lot of 300K mile vehicles in the junkyard due to rusting out, being wrecked, caught in a flood with the original oil still in the transfer case and differentials.

On my non-fording vehicles I do an early change and that will be it for quite a while. My Subaru got a MT/diff fluid change at like 15K miles but that will probably be it until 60k or so.

My 01 truck is only on it's second rear differential fluid change. The only reason it was changed the first time was because the cover rusted out. Transfer case and manual transmission I changed just because I could.
 
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The ATF and diffs are easy to change on my truck. I'm going to do them around 10k or maybe sooner being it's so easy. I'll then let it go until 40-50k, assuming I still have the truck by then.
 
Snagg, a grayish metal paste covered the magnet maybe 1/16-1/8" thick. When wiped off with a rag, it was fine enough that it looked like grease. The next two changes saw successively less paste; that third change just had a very light skim coat of stuff.
 
I want to say I did all of mine at around 25,000 miles...front diff, rear diff, tranny and transfer case. I'll probably do everything again at 50,000 (and this time drop the pan and change the filter).

2018 Silverado.
 
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